Are you referring to the purple tier indicators on armor that signify Tier 4 upgrades?
To provide the most helpful "essay" or detailed breakdown, could you clarify which topic you're interested in? Purple Diamond Armor
Gemology & Jewelry:naturaldiamonds.com/science-of-diamonds/purple-diamonds/">exceptionally rare and formed by geological distortions , often used in high-end bespoke jewelry? Are you referring to the purple tier indicators
Are you asking about Enchanted Diamond Armor , which has a signature purple glint, or perhaps a specific Resource Pack that re-textures standard diamond gear to purple? which has a signature purple glint