THE BLUE-WHITE SCAM: A jeweler tells you, "This is a blue-white diamond." This is a very old term. The dealer will probably tell you that it is a better diamond, but actually it is just the opposite. Blue-white refers to the fluorescence that results in natural light, which contains ultraviolet wavelengths. This blue fluorescence actually makes a colorless diamond look a little oily or milky in sunlight and decreases its value.

THE LIGHT MAKES WHITE SCAM: Bright lights make every mined diamond look better. Of course, every jeweler wants to show his or her diamonds in the best light, but there are some lighting tricks you should avoid. Some bulbs have a strong blue component, which makes yellow stones look whiter. Special bulbs are often used with strong ultraviolet wavelengths, which make most diamonds fluoresce blue. This also has a whitening effect for stones in the lower color ranges.

THE GRADE BUMPING SCAM: A jeweler exaggerates the grade. The FTC says that a jeweler must be accurate within one grade of color and one grade of clarity on a diamond. So many jewelers bump the color and clarity just one grade. Unfortunately, this can mean a great deal of money if you are talking about a fine-quality, 1-carat diamond. For instance, you might find a stone that the jeweler quotes as a 1.00 carat F color / VS1 clarity for $6,500. However, if you sent it to a reputable gem lab like GIA, it would come back as a G color / VS2 clarity, which is only worth about $5,500. This means you lose (and they profit) about $1,000.

THE FRACTION SCAM: The tag says 3/4 carat, and the FTC allows jewelers to round off diamond weights. So a diamond labeled as 3/4 carat in weight might actually weigh anywhere between .69 and .81 carat. This could mean a significant amount of money, since diamond prices leap at certain popular sizes. In this example, you might be buying a .69 carat round G/VS2 worth about $2,100... but paying for what you thought was a 0.75 carat worth $3,000. You lose $900.

THE HIDING THE FLAWS SCAM: Every jeweler hides flaws under the prongs if he can. In many cases, this can make an I1 clarity appear like a VS2 if you look at it in a ring setting. Structural flaws like feathers and cleavages can be damaged by the high pressure exerted by the prong on the diamond to hold it snug in the ring.

THE FRACTURE FILLING SCAM: New treatments to make flaws invisible. There is a new process patented a few years ago that melts a kind of crystal into surface-breaking fractures in a diamond. This technique will slide by consumers unnoticed. The treatment is considered slightly fragile because it can be damaging under the extreme heat of a torch when the diamond is set into a ring. Fracture-filled diamonds should trade for much less than diamonds without this treatment, but in reality they often sell for as much or more because they look like a higher, more expensive clarity grade.

THE CHEMICAL COLOR COATINGS SCAM: A little paint goes a long way. This very deceptive practice involves a little point of blue or purple paint on the lowest tip of the diamond, called the culet. This is small enough that you might not detect it, but the location spreads the color throughout the stone. This counters the yellow tint in lower color grades, making a diamond look like a more expensive, colorless grade.

Man made diamonds or synthetic diamonds are manufactured in a laboratory under controlled conditions. If anything about synthetic diamonds is called into question it is that they are too perfect. And since all mined diamonds have inclusions, flaws, and birthmarks, under magnification a trained jeweler can tell the difference. Considering that man made diamonds cannot be distinguished with the naked eye, lab-created diamonds have aesthetic beauty matching--often besting--mined diamonds, and huge savings are realized, jewelry lovers must regard synthetic diamonds as an intelligent option. Plus, there is no insurance to buy after purchasing man made diamond jewelry and the thousands of dollars in savings can be banked!
About the Author

Robert Joseph is an expert jeweler and founding partner of http://www.diamondnexuslabs.com