Cobalt blue spinel—often nicknamed “peacock blue”—is the connoisseur’s blue: poised, vivid, and quietly luminous. This collector-focused guide explains what defines the color, why it’s prized, and how to evaluate a stone with confidence when commissioning a bespoke, heirloom-quality jewel.

From emeralds to alexandrite, rare gemstones embody both beauty and legacy. Discover Caram’s guide to ranking gemstones by rarity and value — and learn how collectors identify heirloom gems that endure as both treasures and investments.