Cut to the chase

When working with a diamond cutter, he or she usually inspects the stones you’ve submitted and makes recommendations based on your requirements. However, before you decide to restore a diamond (i.e. recutting, repairing, or re-polishing), consider the following:

• What are the gains in terms of cut, colour, and clarity?
• What costs are involved (i.e. shipping, insurance, restoration, and grading)?
• What is the estimated weight loss?
• What will be the increase in value?

If you’re reviewing your inventory for recutting opportunities or considering buying or trading a diamond off the street, here are a few points to keep in mind:

1. Depending on your cutter’s skill, you may be able to achieve colour and/or clarity gains. More about that later.
2. Size matters. Individual stones less than .30 carats are not economically viable, unless you’re prepared to submit a parcel of smalls and wait a little while longer. The golden rule is that if it’s a diamond you’re prepared to send for grading once recut, then it is worth it. Remember, less is more. Most cutters have a minimum cost per diamond for stones that weigh less than one carat and a per-carat rate for stones over one carat.
   • “¨Most diamonds of higher colour and clarity are perfect candidates for restoration, since they are of higher value and worth making the extra investment.
   • “¨For diamonds with lower colour and clarity, consider cutting stones starting at one carat. For example, you’re not going to send a .45-carat J I2 for recut on its own. Instead, add it to a parcel of smaller goods to be restored abroad.
3. Safe margins for weight loss and yields can be calculated using the following:
   • For diamonds in need of a full recut, expect weight loss of up to 15 per cent, assuming the material is not badly damaged or too poor a cut grade to begin with. There are standard formulas for calculating the finished weight that your cutter should be able to provide.
   • For broken, chipped, or damaged diamonds, weight loss can be substantial. It is not unheard of to lose up to 50 per cent to turn these into something you can sell.
   • For diamonds sent for re-polishing to remove minor blemishes like scratches or polish marks, weight loss is in the single digits.
   • A minor repair typically involves some re-polishing to clean up the stone and possibly faceting the girdle, which may result in colour gains on some borderline stones starting from around I colour and upward. This is minor work to improve the diamond’s overall cut grade.