Before you finalize the purchase of your engagement ring, you should take it to a certified appraiser to make sure of its authenticity. Appraisers can be found in the yellow pages or online and can be found in any major city.
Appraisals for diamonds bought on the internet are especially important, since you won't see the actual diamond until it is in your hands. Fortunately, online diamond retailers will usually ship the diamond to an appraiser's office near where you live and once the appraiser has determined that the diamond is indeed of the quality you ordered, the sale is then finalized and you can pick up your ring.
Be wary of any online retailer who will not ship the diamond directly to an appraisers office. Also, you should always check the appraisers office to be sure it is certified and in good standing with organizations like the Better Business Bureau. When choosing an appraiser, use one who is not affiliated with the retailer you purchased the diamond from. If you have homeowners insurance, ask your agent to recommend a good appraiser.