How to Identify Diamond Glass

Diamond glass has been used to simulate diamonds in Europe since the 1700s. At that time, glassworkers discovered that adding lead oxide to glass could give it a few of the visual characteristics found in diamonds; it could increase the light dispersive properties of the glass material along with improving the glass' brilliance. Today, however, we know that diamond glass is simple to distinguish from a real diamond, and can be easily identified with a few visual and home tests.

Things You'll Need

• Towel
• Water
• Clear class cup
• Corn syrup
• Old glass
• Tweezers or pliers

Instructions

Visual Tests

1. Place your finger over one side or the bottom of the stone.

2. Look through the stone to see if the color of your finger shines through the stone. The refractive properties of diamonds will prevent the color from shining through the stone.

3. Ask for a diamond certificate if the seller insists that is a gemstone or a diamond. Look for a symbol from a well-known grading organization, such as the Gemological Institute of America or the American Society of Appraisers.

Breath Test

1. Pinch the stone or setting between your fingers, leaving the top surface uncovered.

2. Blow out a short puff of warm air, such as you would do to fog up a piece of glass. Breathe onto the stone to cloud it over.

3. Inspect the stone to see if the warm air caused fogging over the surface, as diamonds will not cloud over with breath condensation.

Home Test: Corn Syrup

1. Place a few ounces of clear white corn syrup in a clear glass jar or cup.

2. Drop the stone into the corn syrup and allow the stone to slowly sink into the cup.

3. Watch for the stone as it sinks. A true diamond's ability to reflect light will cause it to nearly disappear in corn syrup while glass will be easily visible within the syrup.

4. Rinse the stone of all syrup residue.

Home Test: Heat

1. Place the stone against a warm object such as a warm plate or a hot cup of coffee.

2. Hold the stone in place against the heat source for a few minutes, using tweezers or a small pair of pliers.

3. Place your finger over the opposite side of the stone to see if it is conducting heat. Glass will not conduct heat, while diamond is an excellent heat conductor.

Home Test: Scratch Test

1. Obtain a piece of tough glass like Pyrex cookware or an old porcelain plate. Place it on a towel on a sturdy surface such as a table or countertop.

2. Grasp the stone tightly with fingers or tweezers.

3. Drag the stone across the glass with a firm but even pressure. Repeat this step a few times, with different amounts of pressure.

4. Look at the glass to see if the stone scratched the surface. A true diamond will cut into the glass while a fake diamond will not.

Tips & Warnings

• If you suspect that the stone is old diamond glass, use care to ensure that it is not damaged. While diamond glass is not worth as much as a true diamond, old costume jewelry can be valuable antiques.

References

• Emporia State University: Everything You Always Wanted to Know About a Diamond
• The Boston Globe: How to Tell a Diamond From Glass
• Gemological Institute of America: Diamond Simulants