Most experts recommend purchasing a certified diamond, particularly when buying online, as the best way to ensure value for money.    As a result of strong demand for diamond certifications, many diamond certification labs including GIA, AGS, EGL USA, EGL International, IGI, and others operate worldwide.  The GIA, universally respected as the foremost authority in diamond certification, established a scale of diamond color (D - Z) and clarity (IF - I3) that can help buyers compare diamonds.  All diamond certifications provide grades according to the a similar alpha-numerical scale, but are all diamond certificates the same? 

A recent study by industry expert, Have You Seen the Ring, demonstrates a disturbing trend.   The business reviewed 100 diamonds certified by 5 different labs over a period of 12 months and concluded that the grading scales of the stones varied dramatically.  For example, when an EGL International stone that was a color G and SI2 clarity was viewed next to an EGL USA stone of the same specifications, the former had significantly more yellow color and eye-visible, black inclusions.  While according to the GIA scale, both of these diamonds should be eye-clean and near-colorless, the EGL International G, SI2 looked similar to a GIA J, I1.  The EGL USA stone came closer to GIA specifications at a GIA H, SI2.

When surveyed, nearly 2 out of 5 buyers stated that they were unaware of the differences in certificate standards and that they assumed that color and clarity grades were standardized across all grading labs.   Alarmingly, many buyers of the lower quality stones were not informed of the differences in grading scales when they purchased the diamonds.

So does this mean that buyers should only look at GIA certified stones?  Not necessarily.  Stones from many other labs have a good combination of the 4Cs (color, clarity, cut and carat) and may represent better value for money.  Buyers should beware of diamond prices that are 'too good to be true' and should insist on seeing a copy of a certificate before making a purchase.  The key is to speak with reputable jewelry retailers, who will explain the differences in diamond certifications, and will help choose best stone.