Sapphire White Gold Jewellery Locket.

Sapphire White Gold Jewellery Locket.

By Mannan.

The Logan sapphire, the Star of India, and the Star of Bombay originate from Sri Lankan mines. Madagascar is the world leader in sapphire production (as of 2007) specifically its deposits in and around the town of Ilakaka.

White Gold Jewellery Sapphire Locket.

White Gold Jewellery Sapphire Locket.

By Stone.

Source of color

This issue appeared as a front-page story in the Wall Street Journal on 29 August 1984 in an article by Bill Richards, Carats and Schticks: Sapphire Marketer Upsets The Gem Industry.

Sapphire Gold Jewellery M Necklace.

Sapphire Gold Jewellery M Necklace.

By Stone.

Yogo sapphires sometimes do not need heat treating because their cornflower blue coloring is uniform and deep, they are generally free of the characteristic inclusions, and they have high uniform clarity. 

Multi Color Sapphire Ring Style Locket.

Multi Color Sapphire Ring Style Locket. 

By Stone.

Upon heating, the stone becomes more blue in color, but loses some of the rutile inclusions (silk). When high temperatures are used, the stone loses all silk (inclusions) and it becomes clear under magnification. The inclusions in natural stones are easily seen with a jeweler's loupe. Evidence of sapphire and other gemstones being subjected to heating goes back at least to Roman time

Sapphire White Gold Jewellery Locket chain.

Sapphire White Gold Jewellery Locket chain.

By Stone.

Certain synthetic color-change sapphires have a similar color change to the natural gemstone alexandrite and they are sometimes marketed as "alexandrium" or "synthetic alexandrite". However, the latter term is a misnomer: synthetic color-change sapphires are, technically, not synthetic alex andrites but rather alexandrite simulants. This is because genuine alexandrite is a variety of chrysoberyl: not sapphire, but an entirely different mineral.

Blue Sapphire Star Gold Jewellery Locket Set.

Blue Sapphire Star Gold Jewellery Locket Set.

By Stone.

 The Black Star of Queensland, the second largest gem-quality star sapphire in the world, weighs 733 carats.

Blue Sapphire Gold Jewellery Locket Chain.

Blue Sapphire Gold Jewellery Locket Chain.

By Stone.

Misshapen stars or 12-rayed stars may also form as a result of twinning. The inclusions can alternatively produce a "cat's eye" effect if the 'face-up' direction of the cabochon's dome is oriented perpendicular to the crystal's c-axis rather than parallel to it. If the dome is oriented in between these two directions, an 'off-center' star will be visible, offset away from the high point of the dome.