Antique Sapphire Diamond Gold Engagement Ring at 1stDibs Antique Sapphire and Diamond Ring at 1stDibs Antique Sapphire Diamond Engagement Ring at 1stDibs Antique Sapphire Diamond Engagement Ring at 1stDibs. An antique ring from the early years of the 20th century. Centre stone 5mm diameter (0. 50 carats) Colour H j, clarity Si. Each side a mid colour blue sapphire 4mm diameter. Each end a matching diamond, 3. 7mm (0. 18 0. 20 carats) All diamonds old brilliant cut. Head hand carved 17x6mm, depth 4mm, weight 3. 5grams. Tests as 18 carat gold, no hallmarks required for this period. Size Q, we can resize free of charge.