Vintage 6.90 Oval Cut Sapphire w/ Diamonds in PlatinumVintage 6. 90 Oval Cut Sapphire w Diamonds in Platinum. This impressive sapphire and diamond ring features a diamond filigree antique Art Deco mounting. The center oval sapphire weighs 6. 90 carats and is a deep royal blue with strong saturation and a slightly dark tone. The sapphire is set in a platinum mounting featuring a lattice of bead set diamonds on the angled shoulders of the ring. The total side diamond weight is . 38 carats. This large