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How to Make Dome-Cut Star Sapphires

Star sapphires are gemstones that, when cut correctly, display an asterism or star shape. The appearance of the asterism is due to titanium dioxide present within the stone. Some rubies and other types of gemstones also display this phenomenon. In order to reveal the star in a star sapphire, the stone must be cut and polished very precisely. This process can be challenging even for professional gemstone cutters.

Things You'll Need

Sapphire
Cabbing machine
Gemstone saw
Suede
Aluminum oxide

Instructions

- 1
  Look at the uncut stone to see if you can locate the asterism by sight.
- 2
  If you cannot see the asterism's direction clearly, use the cabbing machine to cut the sapphire into a ball shape.
- 3
  Polish the sapphire with the cabbing machine's polishing wheel or with a piece of suede and aluminum oxide until the asterism is clear. It should be visible on both sides of the optic axis.
- 4
  Cut the ball in half with the saw perpendicular to the optic axis so that you have two dome-shaped cabochons with centered stars.
- 5
  Polish the two stones. A highly polished sapphire will display a better star.

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