Sapphire The Gemstone

Australian Sapphire occurs in the following colours

Blue- light to dark blue, sky blue to a deep blue to almost black
Greens -pale to deep Green aqua, lime, bright green, dark green
Yellows - Canary Yellow , Golden Yellow Sunflower Yellow
Rare Colours Apricot, Purple, Orange, Peach
Colour Change These stones display a change in colour when viewed under different lights. Daylight to fluorescent or incandescent
Parti Colour these stones have a mix of two or more colours most common are green/blue and blue /yellow particolours though any colours can be mixed some truely spectacular stones are particolours
Almost any shade or colour is possible the value of any particilar colour depends on its scarcity T

The Technical data

Sapphire is the gem quality form of Corundum. It is second only to Diamond in hardness. The hardness of corundum is due in part to the strong and short oxygen-aluminum bonds. These bonds pull the oxygen and aluminum atoms close together. This makes the crystal not only hard but also quite dense for a mineral made up of two relatively light elements.

- Chemical Formula: Al2O3, Aluminum Oxide
- VARIETY OF: Corundum , Al2O3 .
- USES: Gemstone (for high grade material) and abrasive
- BIRTHSTONE FOR: September
- Main Colours: blue, green, 'parti' (a mix of colours)& yellow
- Rare Colours: Golden Yellow, orange, apricot, purple, pink, red(Ruby)
- The pink to red colour of ruby stems from its chromium content, whereas the sapphire's blue results from its titanium content. Yellow and green sapphires contain variable amounts of ferrous and ferric iron.
- INDEX OF REFRACTION: 1.76 - 1.78
- BIREFRINGENCE: 0.009
- HARDNESS: 9
- Luster is vitreous to adamantine.
-Transparency: Crystals are transparent to translucent.
- Crystal System is trigonal; bar 3 2/m
- Crystal Habits include sapphire's typical six-sided barrel shape that may taper into a pyramid, and ruby's hexagonal prisms and blades.
- Specific Gravity is approximately 4.0+
- Cleavage is absent, although there is parting which occurs in three directions.
- Streak is white.
- Other Characteristics: Refractive index is around 1.77; pleochroic (meaning color intensity is variable from different viewing directions); striations
 

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