Vintage Art Deco Lady's Platinum Sapphire & Diamond Ring Stamped "PLAT". Ring Size: 4.75 One Round Cut Diamond weighing approx. 0.90ct Six Round Cut Sapphires. Twelve Round Cut Diamonds. A supreme example of platinum Art Deco jewelry at its finest. The center diamond appears to be about ninety points and the sapphires are certainly Burmese. They have that deep and wonderful color that only Burmese sapphires have. I examine you to examine the picture to see all of the scrolling and filigree. When working in platinum, which has a higher melting point than the sun is hot, it is very difficult to create anything as beautiful as this.