At least know the four 'Cs' to ensure that the diamonds you buy make the grade

You don't have to be a diamond expert, but a little knowledge goes a long way to ensuring you get a good stone for your money.

It might look good, even through the magnifying glass, but don't cut corners in a bid to get a bargain, or risk a fortune on a precious gift or investment without following this basic advice:

"You should never buy a diamond without a certificate," says Ari Epstein, the CEO of the Antwerp World Diamond Centre. And it is also important to make sure it's the right certificate.

Normally a certificate includes information about the four Cs - color, clarity, cut and carat weight - along with a diagram of its clarity characteristics and a graphic representation of the diamond's proportions.

The brilliance of a diamond depends more on its cut than any other factor. The clearer a diamond, absence of impurities and blemishes, and the less color it has, the higher its value. And it is weighed in metric carats: one carat equaling 0.2 grams, about the weight of a paperclip.

There are two kinds of diamond certificates in the market. One is from the HRD Antwerp Institute of Gemology, a wholly owned subsidiary of AWDC. Most diamonds in Antwerp are sold with HRD certificates.

The other is from the Gemological Institute of America. It is considered slightly stricter in standard.

"The grading process is still done by humans like it was hundreds of years ago," says Viviane Dayekh, of Dayekh Diamond in Antwerp. "Computers or any other machines cannot replace us in this procedure."

She says most customers are cheated because they lack basic knowledge about diamond grading. Knowing the 4Cs standard and the price chart are crucial homework for a customer before purchase.