BACKGROUND This study aimed to compare a composite resin (Duo-Shade) shade guide with Vita ceramic shades before/after chemical and autoclave sterilization. MATERIAL AND METHODS Color values (L*a*b*) were recorded directly from shade tabs of prefabricated composite resin (Brilliant NG Universal Duo-Shade) and ceramic (Vita classic) shade guide with a calibrated spectrophotometer (Vita Easy Shade Advance 4.0). Seventy-two composite resin disk samples with 6 different shades (A1/B1, A2/B2, A3/D3, A3.5/B3, A4/C4, and C2/C3) (n=12 each) were divided into 2 groups (Gp) - Gp A (Autoclave) and Gp C (Chemical) (15 cycles) - to assess their influence on respective shades. Mean values calculated the color differences (ΔE) while differences in color values (L*a*b*) were graded on the National Bureau of Standards (NBS) 6-grade scale and assessed for Clinical Acceptance/Perceptible Threshold (CAT), (CPT). All differences were considered significant if the color difference ΔE was ≥3.3. RESULTS Only 2 out of 12 Shade tabs (C2C3, A4C4) of composite resin matched to Vita shade tab C2 and C4 (ΔE ≤3.3). Both groups showed notable color differences after respective sterilization protocols, with color differences in Gp A significantly higher than Gp C (DE ³3.3). Within groups, all shades in Gp A showed remarkably different color changes, with shade C2C3 and A1B1 being denoted as clinically unacceptable. CONCLUSIONS Manufacturer-provided shade guides do not match ceramic shades as claimed and chemical sterilization using 10% Deconex was associated with less color changes than with autoclave sterilization.