I have had a jeweller test this etc.. It is not hallmarked but tests as platinum and holds a superb colour large ceylon sapphire. As an estimate 2ct measuring a rectangle of 7mm x 5 mm with good depth to the stone. There are 4 diamonds , 2 each side weighing approx 15-20 points total. The ring is currently a small G/H but is resizable.The item "Stunning Antique Art Deco Rare Platinum Diamond And Ceylon Blue Sapphire Ring" is in sale since Wednesday, August 15, 2018. This item is in the category "Jewellery & Watches\Vintage & Antique Jewellery\Vintage Fine Jewellery\Art Deco (1915-1935)". The seller is "9duck" and is located in Plymouth. This item can be shipped worldwide.