Pearl Luster Research Articles

Preparation of WO3-Mica Hybrid Coatings with Electrochromic Properties and Pearl Luster.

Tungsten oxide-mica composites were prepared by adding different amounts of commercial mica (alumina silicate) in order to provide high luster to electrochromic coatings. The mechanical stability was sustained for up to 50 weight % mica for application in aqueous medium. The electrochemical properties, coloration, and luster were investigated. The luster of the composites increased roughly linearly with increased mica content and was retained after coloration. The addition of 10 weight % mica was found to be optimal with respect to the compromise between electrochromic coloration and pearlescent luster. This is, to the best of our knowledge, the first report on the preparation and characterization of WO3-mica inorganic composites with high luster in both bleached and colored states.

Using optical coherence tomography to assess luster of pearls: technique suitability and insights

Luster is one of the vital indexes in pearl grading. To find a fast, nondestructive, and low-cost grading method, optical coherence tomography (OCT) is introduced to predict the luster grade through the texture features. After background removal, flattening, and segmentation, the speckle pattern of the region of interest is described by seven kinds of feature textures, including center-symmetric auto-correlation (CSAC), fractal dimension (FD), Gabor, gray level co-occurrence matrix (GLCM), histogram of oriented gradients (HOG), laws texture energy (LAWS), and local binary patterns (LBP). To find the relations between speckle-derived texture features and luster grades, four Four groups of pearl samples were used in the experiment to detect texture differences based on support vector machines (SVMs) and random forest classifier (RFC)) for investigating the relations between speckle-derived texture features and luster grades. The precision, recall, F1-score, and accuracy are more significant than 0.9 in several simulations, even after dimension reduction. This demonstrates that the texture feature from OCT images can be applied to class the pearl luster based on speckle changes.

High solid content preparation of size controllable BiOCl crystals as pearlescent pigment in solvent-free polyurethane coating

In the current research, we are committed to solving the irreconcilable contradiction between fragmentation, agglomeration, poor size controllability, and high solid content in the preparation of BiOCl crystals. Water soluble block polymer polyethylene glycol monomethyl ether-b-polydimethylaminoethyl methacrylate (mPEG-b-PDMAEMA) was synthesized as dispersant to achieve high solid content by reducing the frequency of crystal collisions to avoid crystal fragments and agglomerates. With the reaction temperature of 80 °C, urea dosage of 40 g, bismuth salt solution addition rate of 0.45 ml/min, and variable amount of pre-added HCl in the reaction vessel, fragment-free BiOCl crystals of wide size ranges were successfully obtained with record-high solid content of above 10 wt%. Furthermore, bio-based pearlescent coatings were prepared by using as-synthesized BiOCl crystals as pearlescent pigments and polyglyceryl tetrastearate and polyphenyl polymethylene polyisocyanate (PAPI) as the formulations of two-component solvent free polyurethane. The decorative polyurethane coatings demonstrated excellent physical properties and corrosion resistance, which exhibited eye-catching gloss effects from pearl luster, glitter pearl luster, to shimmering luster derived from the size variation of 20, 50, and 70 µm, respectively. The large-scaled production of size controllable BiOCl crystals with high solid content in wide size range promises the practical applications in decorative coatings, cosmetics, clothing accessories, and car interior accessories.

Estimation of non-nucleated pearl quality traits from donor and host mussel-derived genetic parameters in the golden strain of Hyriopsis cumingii

Hyriopsis cumingii is the most important freshwater mussel for pearl production in China and its pearl color is polymorphic. In order to establish a selective breeding program, the genetic parameters of growth and inner shell color traits of golden H. cumingii were evaluated in our lab. Due to the long culture time for pearl production, very little is known about the genetic parameters of commercially important pearl traits. In this study, the genetic parameters of donor-derived and host-derived pearl quality traits were estimated and the genetic contribution from donor and host interaction to pearl quality traits was analyzed. In addition, the correlation of pearl traits with growth traits, inner shell color and luster of donor and host mussels was examined. Microsatellite-based DNA parentage analyses were used to assign mussels to families and populations of origin. A total of 653 individual mussels could be clearly assigned to eight paternal half-sib and 39 full-sib families. Five pearl traits that constitute the major determinants of pearl value (color, luster, size, weight and roundness) were recorded at harvest. Pearl weight and size were significantly correlated with growth traits of the host mussel, while pearl color and luster were significantly correlated with the inner shell color and luster of the donor mussel. Our results indicated that the b⁎ value may be a representative parameter for the evaluation of pearl color in the golden strain in Hyriopsis cumingii. Donor-derived heritability estimates for pearl luster (h2 = 0.37) and color b⁎ values (h2 = 0.47) were high, while heritability estimates for pearl weight (h2 = 0.16), size (h2 = 0.18) and roundness (h2 = 0.07) were low to moderate. By contrast, host-derived heritability estimates for pearl luster and color were low to moderate, while heritability estimates for pearl weight (h2= 0.28), size (h2= 0.24) and roundness (h2 = 0.16) were moderate. The genetic contribution of the donor and host (D × H) interaction on pearl color and pearl luster were low, while the genetic contribution of the D × H interaction on pearl size, weight and roundness were moderate to high. This study revealed the possibility of promoting different selective breeding programs for improving host and donor mussels. Selecting mussels with excellent luster, golden color and higher growth traits as the donors and mussels with excellent growth traits as the hosts may cultivate bigger and brighter golden pearls.

Impact of Culture Period on Quality of Image Pearls Produced by the Freshwater Mussel, Lamellidens marginalis, in Bangladesh

Pearls are gems produced by biological processes within the living tissues of molluscs. Image pearls are a form of blister pearl that portray a design or image such as a bird, fish, flower, goddess, etc. To achieve this, a paraffin wax mold is inserted between the shell and the mantle of a freshwater mussel and subsequent nacre coverage produces an image pearl after an appropriate culture period for the mussel. The optimum culture period has not yet been determined to maximize the quality of image pearls produced in Bangladesh, and this knowledge gap was addressed in this study. Image pearl production using the freshwater mussel Lamellidens marginalis was conducted over three culture periods (T 1 = 7 mo, T 2 = 9 mo, and T 3 = 11 mo). A total of 3,150 mussels were implanted with 2.5 × 1.5 cm2 paraffin wax molds, with 1,050 mussels allocated to each treatment, which had five replicates. Survival and pearl production rate of mussels were negatively correlated with culture period. Survival and pearl production rate were 14.7%, 12.3%, and 11.9% for mussels cultured for 7, 9, and 11 mo, respectively. The thicknesses of the nacre making up the image pearl and pearl luster were both improved with longer culture periods. The highest quality pearls with a mean nacre thickness of 0.71 mm were produced after 11 mo. Pearls produced after 11 mo also had the highest luster (40.05 lux) compared with pearls cultured for 7 mo (12.85 lux) or 9 mo (30.2 lux). There were statistically significant differences at the P < 0.05 level in survival rate F (2, 12) = 9.40, P = 0.004 and nacre layer thickness F (2, 12) = 13.30, P = 0.001 between T 1 and T 3. The results indicated that image pearls with high luster and improved quality are produced after longer culture durations and confirms the influence of culture period on image pearl production and quality. Further research is required to improve image pearl production methods and pearl yield.

Application of coconut oil from Ben Tre Province (Vietnam) as the main detergent for body wash products

Coconut oil is considered the active ingredient as a moisturizer used by many people in tropical regions. At the same time, coconut oil can improve the symptoms of skin disorders by moisturizing and soothing the skin. A body washes formula that contains coconut oil based on the saponification process is formulated through an appropriate content survey. The combination of auxiliary substances such as detergent, foaming agent, moisturizing agent, preservative was also conducted to evaluate different concentrations. Products are assessed and visually observed for appearance, viscosity, pH value, stability, and durability when stored. The body wash formula was found to be white and pearl luster was visually observed. Products using 20% crude soap content, 5% detergent (SLES), 3% glycerin, etc. have all been tested to show good physico-chemical properties in terms of pH value and viscosity, as well as no irritation, upon skin contact. Research shows that coconut oil body wash formulas with good physico-chemical properties can be developed into new body wash cosmetic products.

Pearl luster and shelf-life enhancement through pearl treatment

Pearl luster and shelf-life enhancement through pearl treatment

Origin of Saddle Dolomite in Aqra - Bekhma Formation (Upper Campanain - Mastrichtian), Bekhma Gorge Area, North Iraq

Thirty-four dolomite and dolomitic limestone samples were collected from Aqra – Bekhma (It is difficult to separate the two formations as they are intervening) Formation in Bekhma Gorge area near Shaqlawa in northern Iraq. Alizarin red - s was used to distinguish calcite from dolomite. The saddle dolomite was recognized as a virtually rough crystalline material with milky-white or rosy color when seen in outcrop. In addition, we observed a pearl luster and a characteristically marred crystal building that is, in principle, described as damaged crystal faces with cleavage planes, while microscopically it appeared as a widespread extinction. The crystal faces, although well advanced, are frequently pavement-like facets.

The effect of different culture methods on the quality of round pearls produced by the black-lip pearl oyster Pinctada margaritifera (Linnaeus, 1758)

A range of culture units and husbandry methods may be used for pearl oysters and the two most commonly used for Pinctada margaritifera are panel nets and chaplets. In this study, six hundred P. margaritifera were grafted for the first time and cultured using panel nets or chaplets at three commercial farm sites to determine if these different culture methods influences resulting pearl quality. The pearls produced were compared in terms of size, shape, lustre, colour, surface perfection and overall quality. The highest proportion of pearls produced in all treatments was in the 10–11mm size category (37–54%) but culture method did not significantly (p=0.211) influence the size of pearls produced. Oysters held on chaplets produced more pearls with concentric surface grooves or ‘circles’ (47–60%) compared to oysters in held panel nets (43–45%) at all three culture sites. Oysters held in panel nets produced higher proportions of pearls in the more desirable ‘round’ and ‘semi-round’ shape categories (6% and 25%, respectively) than oysters held on chaplets (5% and 15%, respectively) at all three culture sites, and culture method had a significant impact (p=0.031) on pearl shape overall. Higher proportions of pearls in the ‘very high’ and ‘high’ lustre categories (8% and 40%, respectively) were produced by oysters held in panel nets compared to those on chaplets (3% and 16%, respectively) at each of the three culture sites. However, the overall impact of culture methods on pearl lustre was not significant (p=0.100). At all three culture sites, higher proportions of pearls assigned to grades ‘A’ (6%) and ‘B’ (46%) were produced by oysters in panel nets compared to those held on chaplets where 3% and 29% of pearls were assigned to grade ‘A’ and grade ‘B’, respectively. Oysters held on chaplets produced higher proportions of grade ‘C’ (49%) and grade ‘D’ (19%) pearls than those in panel nets (39% and 9%, respectively) at all three culture sites. The grades of pearls were significantly influenced (p=0.035) by culture method. This study clearly demonstrated the benefits of pearl production using panel nets compared to the traditional chaplet-based system used by the majority of pearl farmers in Fiji and throughout the Pacific. Pearls production using panel nets will provide better returns with higher profit margins for pearl farmers but requires greater outlay for infrastructure and labour that may be beyond the scope of most pearl farmers in Fiji and the Pacific. A detailed cost–benefit analysis of the two husbandry options would be beneficial to pearl farmers. Statement of relevanceThis paper presents novel new information showing that grafted P. margaritifera cultured using panel nets produced pearls with fewer ‘circles’ and of higher quality and value than oysters cultured using chaplets. The potential benefits to pearl farmers of pearl production using panel nets compared to the more traditional chaplet-based system are clear and the results of this study support improved pearl quality and income for pearl farmers in the Pacific.

Influence of nacre deposition rate on cultured pearl grade and colour in the black-lipped pearl oyster Pinctada margaritifera using farmed donor families

Cultured pearl nacre deposition rate in Pinctada margaritifera oysters was studied to examine its influence on Tahitian classification grade and colour and to further our understanding of using selected donor oysters produced in a hatchery system for the improvement of these traits. A large-scale grafting experiment using 150 farmed donor oysters was realised in Rangiroa atoll (French Polynesia). After 18 months of culture, 874 pearls were harvested and 7 pearls quality traits were recorded: (1) nacre deposition rate assessed by nacre thickness and weight, (2) classification grade, lustre and surface defects, and (3) colour assessed by pearl colour darkness level and visual colour categories. Nacre deposition rate significantly influence pearl grade, surface defects, darkness level and colour categories, but not the lustre. Grade A pearls had the thickest and heaviest nacre on average, compared with grade D pearls and rejects. In addition, pearls without any surface defect had thicker and heavier nacre. Pearls with low darkness were the thinnest and the lightest. Pearls of aubergine–peacock secondary colours were the thickest and the heaviest. These results highlight the importance of rapid nacre deposition rate for increasing the production of grade A pearls, with less surface defects and dominance of a black tone colour. Fast nacre deposition may, however, have a negative impact on other pearl quality traits, such as pearl lustre. This study demonstrates the importance of examining relationships between pearl quality traits in a way that provides solid information that can be directly used for breeding and genetic selection programmes.

The Use of UV-Visible Reflectance Spectroscopy as an Objective Tool to Evaluate Pearl Quality

Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl’s quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry.

아코야 진주의 화학조성과 내부구조가 진주광택에 미치는 영향에 관한 연구

우리는 같은 지역에서 생성된 진주의 표면품질 차이점의 원인을 다양한 분석을 통해 분석하고자 하였다. 본 연구들을 토대로 진주의 표면품질은 진주를 구성하고 있는 아라고나이트와 방해석의 함유량의 차이에 의해 발생되는 것으로 추정되었다. 또한 내부 구조분석을 통해 표면품질이 서로 다른 진주의 발생원인은 내부구조와 일정한 연관성이 있는 것으로 판단되었으며 진주의 생성환경 또한 영향을 줄 것이라 사료되었다. 하지만 앞서 실시한 대부분의 실험들이 파괴분석이며 이러한 분석들은 진주와 같은 가치 있는 시료에 부적합하므로 앞으로 새로운 방법의 실험들이 진행되어야 할 것이다. The patterns in X-ray diffraction (XRD) spectroscopy provide useful clue at <TEX>$29.4^{\circ}$</TEX> to discriminate two types of Akoya cultured pearl which occurs difference of surface luster. Using the optical microscope, we could be confirmed that the nareous layer of each sample consist of different crystal form. In Fourier Transform Infrared (FT-IR) Spectroscopy analysis, the nareous layer of Akoya cultured pearls with poor luster shows some peaks at 712, 699, 1435, <TEX>$1444cm^{-1}$</TEX> region and these peaks depend on the Calcite. But the nareous layer of pearls with excellent luster could not observed those peaks related with Calcite, we could observed Aragonite band at 699, <TEX>$1085cm^{-1}$</TEX> region. Though this result, we know that the nareous layer of Akoya cultured pearls with excellent luster is mainly composed by Aragonite. Raman bands are also clearly demonstrated to occur difference of band intensity by difference of Aragonite content. In the Scanning Electron Microscope (SEM) analysis, we found that the Akoya cultured pearl luster and surface condition is associated with internal structure.

Assessing Pearl Quality Using Reflectance UV-Vis Spectroscopy: Does the Same Donor Produce Consistent Pearl Quality?

Two groups of commercial quality (“acceptable”) pearls produced using two donors, and a group of “acceptable” pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones) showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver) showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected with UV-Vis spectrophotometry. Nevertheless, this technique could have a role to play in developing less subjective methods of assessing pearl quality and in further studies of the relationships between pearl quality and that of the donor and recipient oysters.

Preparation of Color Pearlescent Pigment Using Rare-Earth Oxide and Titanium Oxide to Coat Mica

The rare earth of Er2O3, Nd2O3, Pr6O11 as pigmentation-type coating materials was used to coat the surface of mica by wet chemical deposition method. Then the color pearl luster pigment was synthesized by heat treatment. The coating was carried out by multiple-coating technique and the influence of technique parameters on the coating was studied systematically.

Characterization of Pearl Luster Pigments

AbstractThis paper presents current developments in pearl luster pigments. After a short introduction on the application of pigments, the synthesis and characterization of a ZrO2/SiO2 based pearlescent pigment will be described. The applied methods for characterization were ex situ x‐ray diffraction (XRD) of dried and calcined pigment powders, in situ XRD in a temperature range from 100°C up to 850°C and transmission electron microscopy (TEM) of thin cross‐sections. The XRD measurements were used for phase analysis, determination of cell parameters and average crystal grain sizes. A special preparation method was developed for TEM cross section specimens for platy like pigment particles. The microstructure, the interface between substrate and coating material and the particle sizes are described with high resolution TEM pictures of cross section specimens. The basic interest is the behaviour of the zirconium dioxide coating during sintering in order to achieve a condensation of the film without any further crystal grain growth.

Pearl lustre pigments give plastics an edge

Pearl lustre pigments can provide plastics with special effects and a distinctive look. Plastics Additives & Compounding looks at recent developments at one of the company's active in this area, Merck. The company has developed the Iriodin range of products offering new options in product design, as well as in laser marking.

Pearl luster pigments as overheating protection in transparently insulated solar façades

Transparently insulated (TI) walls are an efficient means to reduce the heating demand of buildings. However, large scale use of TI is still not realized, basically due to overheating problems. Mechanical shading devices are expensive and may malfunction. Furthermore, the lack of acceptance from architects because of the missing color-designability remains an unsolved problem. A promising solution for both mentioned points is a coating of pearl luster pigments on the TI wall. These pigments show an angle-dependent transmittance and reflectance and their color is variable. The pigments are structured similarly to natural pearls, where the color is caused by an interference effect of multiple layers with alternating refractive indices. A model for radiation transfer in the pigments has been derived and verified experimentally. The model can be used to design pigments with tailor-made properties. Based on insolation data from the test reference year for Wuerzburg, Germany (TRY05), the ideal cut-off angle which depends on the latitude has been calculated for a middle-European location, considering direct and diffuse solar radiation. This allows to derive the energy savings potential of TI walls covered with optimized pearl luster pigments. Finally, a 1.6×2.4 m 2 glass cover, equipped with selected pigments, was installed at the ZAE test facility in Wuerzburg. These experiments show that the heat flux into the room in summer is reduced drastically and overheating can be prevented.

Influence of different-shaped pigments on bisacodyl release from Eudragit L 30 D

Self-prepared bisacodyl pellets were coated in a miniature fluid-bed pan coater with Eudragit L 30 D plasticized with dibutyl phthalate (DBP) or triethyl citrate (TEC) and containing different types of pigments, e.g., titanium dioxide, red iron oxide, talc, mica and platelet-shaped pearl luster pigments with titanium dioxide or iron oxide surfaces, respectively. The pigment volume concentration within all coatings was the same. Dissolution tests in artificial gastric fluid showed that platelet-shaped pigments or fillers, independent of their chemical constitution and polarity of their surfaces, reduce drug release from Eudragit L 30 D. Coarse platelets have a greater effect than finer ones. Coatings with spherical titanium dioxide and red iron oxide needles have no barrier effect or even lead to an increase in permeability depending on their concentration within the coating. Drug release from films plasticized with DBP was slower than from films with TEC. DBP therefore is more suitable for Eudragit L 30 D than TEC.