How To Test a Diamond at Home
The technology involved in producing fake diamonds is quite advanced, making it difficult for the average person to spot a fake. To definitively identify a fake you need the proper equipment. However, you can perform a few simple tests to help determine the authenticity of a diamond. While these tests are not conclusive, they can be helpful.
The size of the stone will affect your ability to read the results of these two tests. Larger stones provide more surface area to observe.
1. The Breath Test
Diamonds have thermal conductivity characteristics; i.e. they can conduct heat. Fake diamonds do not have the same ability. Breathe on the stone as you would a mirror or window to fog it. If you can see fog or condensation on the stone, it is not a diamond. Diamonds disperse the heat of your breath so that condensation does not form.
2. The Reading Test
Diamonds have clarity, which allows you to see through them. Place the stone on a printed document with the table against the document. The table is the large, flat facet on the top of the stone. Look through the stone. If you can read the document, the stone may be a real diamond. Very low quality fake diamonds can pass this test.
The next tests are easier to perform at home and are not dramatically affected by the size of the stone. Beware of the light test, very high quality real diamonds do not pass it.
3. The Fluorescent Test
Hold the stone under a black light or ultraviolet light. Many diamonds will fluoresce blue under these light waves. If the stone fluoresces it is probably real. If it does not fluoresce, it could be a very good diamond or it could be fake.
4. The Weight Test
One of the most common fake diamonds is the cubic zirconium. This fake weighs about 50 percent more than a comparably sized diamond. If you know how much your diamond should weigh you can compare that number with the stone's actual weight. For this test you will need a very precise scale, such as a jeweler's scale. A one-carat diamond will weigh approximately 0.2 grams. That is the weight of the diamond without the setting.
5. The Loop Test
This test requires the use of a jeweler's loop or high-grade magnifying glass. Use the loop to examine the stone for the following characteristics of real diamonds.
- Facets with sharp, not rounded, edges
- Faceted girdle
- Imperfections; all real diamonds have imperfections in the stone
- Quality setting; fake diamonds are typically not set in high quality metals
The above tests can help determine if a diamond is a fake, but they are not conclusive. The only way to know for sure, without a professional appraisal, is to use a diamond tester.
6. The Diamond Tester Test
These devices measure the stone's thermal conductivity to determine if it is a diamond or not. Diamond testers are available from jewelry supplies. The cost ranges from $70 to $100's. A more cost effective approach is to obtain a professional appraisal, which will provide you with certification of the diamond's characteristics.