Size 5.75 Weight: 8.63 Grams Gemstones: .66ctw Natural Alexandrite, .47ctw Natural Diamonds SI clarity, G-H color metal: platinum pt900 Notes from the Curator First discovered in Russia's Ural Mountains in the 1830s, alexandrite owes its color-change phenomenon to chromium substituting for aluminum in its chrysoberyl lattice—a shift arising not from pleochroism but from the mineral's unusual light-absorbing properties. This ring's three round-cut natural alexandrites, totaling 0.66 carats, are arranged in a two-tier cluster with baguette-cut diamonds radiating outward in a scalloped halo—a design language rooted in mid-century ballerina and cluster compositions that emphasized geometrical symmetry and stepped silhouettes. The PT900 hallmark denotes 900 parts per thousand platinum purity, a standard widely used in Japan, Europe, and elsewhere, and its 10-percent alloy content renders it harder and more wear-resistant than PT950, making it particularly suited to the delicate prong work required for multiple stone settings. Most cut alexandrite gems weigh less than one carat, and the presence of three stones in a single mount—complemented by nearly half a carat of white diamonds—speaks to the rarity and deliberate composition of this piece, which captures the stone's chameleon identity across a constellation of stones rather than a single solitaire.