A Magical Purple Star Sapphire and Diamond cluster ring. An enthralling treasure composed of a large round Purple Star Sapphire mounted in a collet setting within a surmount of 28 Brilliant Cut Diamonds to a pierced gallery and a heavy tapering shank. The Diamonds weigh approximately 0.30cts in total and the sapphire weighs approximately 10cts. All set in yellow. Tested as 18ct Gold.
A star sapphire is a type of sapphire that exhibits a star-like phenomenon known as asterism. Star sapphires contain intersecting needle-like inclusions (often the mineral rutile) that cause the appearance of a six-rayed 'star'-shaped pattern when viewed with a single overhead light source. Various shades of blue [dark and light] result from titanium and iron substitutions in the aluminium oxide crystal lattice. Some stones are not well saturated and show tones of gray. It is common to bake natural sapphires to improve colour. This is usually done by heating the sapphires to temperatures of up to 1800 øC for several hours, or by heating in a nitrogen deficient atmosphere oven for 7 days or more. On magnification the silk due to included rutile needles are visible. If the needles are unbroken, then the stone was not heated. If the silk is not visible then the stone was heated adequately. If the silk is partially broken then a process known as low tube heat was used. Low tube heat is the process where the rough stone is heated to 1300 øC for 20 to 30 minutes over charcoal. This takes out any gray or brown in the stone and improves colour saturation. Purple sapphires contain the trace element vanadium and come in a wide variety of shades. Yellow and green sapphires have traces of iron which gives them their colour. Pink sapphires have a trace element of chromium and the deeper the colour pink the higher the value as long as the color is going toward red of rubies. Sapphires also occur in shades of orange and brown, and colourless sapphires are sometimes used as diamond substitutes in jewelry. Salmon-colour padparadscha sapphires are orangy-pink, pinkish-orange, or pink-orange in color and often fetch higher prices than many of the finest blue sapphires. The word 'padparadscha' is Sinhalese for 'lotus flower'.
A Purple Star Sapphire and Diamond cluster ring. Sapphire 10cts approx. Diamonds 0.30cts approx. SOLD