ABSTRACT This study investigates the color values and colorfastness of silk fabrics dyed with dye extracted from Water Jasmine (Wrightia religiosa Benth.) using three different alkaline agents: red lime, lime, and sodium carbonate. The color values (L*, a*, b*, C*, h*, and K/S) were measured before laundering to evaluate the color characteristics of the dyed silk. Notably, red lime produced the deepest shade (L* value of 50.46), closely followed by lime (77.07) and sodium carbonate (59.48). The h* values indicated that red lime (246.83) and sodium carbonate (292.17) produced blue shades, while lime (92.54) leaned toward green-yellow. Regarding color strength (K/S), red lime and sodium carbonate exhibited the highest color strength (1.74), whereas lime had the lowest (0.59). After laundering, colorfastness was evaluated using DL*, Da*, Db*, DC*, DH*, and DE* values. Red lime showed the best color durability, with a DE* value of 6.46, indicating fair color retention. Lime and sodium carbonate had poorer color durability, with DE* values of 12.05 and 16.15, respectively. Thus, the results clearly show that Water Jasmine with red lime possesses significant potential for development as a natural dye source, specifically for creating novel blue-colored natural dye material for silk dyeing.