Diamonds, gold, iron, and emeralds remain fully opaque and are often given brighter outlines for easier spotting.
How To Get XRay in Minecraft Java 1.21.10 (XRay Texture Pack) xray texture pack 188 updated
Replaces the textures of stone, dirt, and gravel with near-invisible glass-like surfaces, allowing you to see through the ground. Diamonds, gold, iron, and emeralds remain fully opaque