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How to Determine a Linde Star

Linde Stars are synthetic star sapphire stones that the Linde division of the Union Carbide Air Products Company patented in 1949. The Linde division only produced Linde Stars until 1974. These stones are recognized by their distinctively sharp, six-sided asterisk centers and clear blue color. They are less expensive than natural star sapphires, but are popular with collectors. Linde star sapphires also have more clarity than natural star sapphires and they are easy to mold. These stones are therefore used in lasers and precision instruments as well as for jewelry.

Things You'll Need

Flashlight

Instructions

- 1
  Look at the edge of the stone. If it is a perfectly rounded circle, the stone is synthetic and likely is a Linde Star.
- 2
  Shine a flashlight directly on the surface of the stone. Look at the arms of the star; if they are equal lengths and perfectly straight, the stone is likely synthetic and possibly a Linde Star.
- 3
  Move the beam of light around the surface of the stone. If the star doesn't move along with the beam of light or it only moves in one direction, it is a synthetic stone and potentially a Linde Star.
- 4
  Turn the stone over and look at the bottom for a stamped letter "L." This stamp is used to mark all Linde Star synthetic sapphires. If the stone bears this stamp, it is a Linde Star.

Rock Collecting