Blue and tantalizing... Charming and effervescent! For centuries, blue gemstones have been used as a symbol of prosperity, fertility and compassion. Sapphire gemstone has traces of iron and titanium with impeccable hardness. There are many varieties of sapphire. Blue and yellow sapphires are most common and garner lot of popularity in the natural stone market. Buying sapphires can test even the best of stone collectors. Here are 8 things you must know while buying sapphires from the stone market.
Natural and artificial gemstones from sapphire family are available in more than 50 different shades. The base shade of sapphire stones includes colours like:
Sapphire gemstone made of corundum is sold in “fancy” package and not as semi-precious varieties. In a single gemstone family, you can get many colours with consistent hardness and clarity.
Sapphire gemstones have a consistent colour up to a certain temperature. When exposed to higher temperatures beyond 650 degrees Celsius, the colour and clarity of the stone tend to get distorted. Natural gemstones from Sapphire family tend to get cloudy, milky or turn pale. There is no effect on hardness.
After mineral corundum, sapphire gemstone is the hardest mineral. On Mohs scale, it ranks 9. Gem quality of the stone is extremely rare, especially if you are looking for consistent colours. Harder gemstones tend to have opaque colours compared to the softer varieties.
- Sapphire with Blue is rare
Intense blue sapphires are rare and more expensive. It is because only a small percentage of blue sapphires display vibrant colours. The lighter gemstones in the family are artificially treated to enhance the colour as well as hardness. Red and blue sapphires now have a separate lineage. Red varieties are counted as rubies. Red sapphire gemstones are cheaper than the red rubies though.
- Look for natural sunlight
Always test a sapphire under natural sunlight. The colour may vary from dark electrifying blue to royal ink blue. Some untreated gems appear red in sunlight and are susceptible to fractures along the differential colour streaks.
Sapphire gemstone lacks any form of cleavage. They display uneven fracture with a conchoidal contour. With a refractive index ranging between 1.762 and 1.788, the gemstone exhibits tri-axial symmetry along four axes.
Owing to the colour, the sapphires are often confused with gemstones like Iolite, blue Tourmaline, spinel, zircon, beryl, tourmaline and chrysoberyl. There are limited regions in the world that produce natural sapphires. Burma, Kashmir in India and Sri Lanka have always been the top contributors of the gemstone.
Other significant sources are Thailand, Vietnam, Tanzania, USA, Australia and Madagascar.
Finest quality gemstones are available in the market based on the auction prices. The finest sapphires come from Kashmir and Mogok. Burmese sapphires and Ceylonese sapphires are stacked in a price range of USD 2000 per carat and above. Collectible gemstones of size larger than 5 carats are available only through auctions.