'Follow the simple rules when buying'
"If you're going to spend more than €2,000 then follow some simple rules", says gemmologist Carol Clarke. "Buy only GIA certified stones, laboratory graded, pay by credit card and have it valued by a qualified gemmologist (not necessarily a jeweller).
"Diamonds are assessed by the 4 Cs: carat (weight), cut (which affects light refraction), clarity (from internally flawless to a range of inclusions) and colour (D is clearest down to X which is yellow).
"If you buy abroad, particularly in New York they often sell 'perfect' looking diamonds which have had any inclusions lasered out and re-filled with a type of resin; under US Federal law they're supposed to disclose it, but often don't and in heat, or after a knock it disintegrates, seeps out or shatters.
"I've seen lots of those cases over my 30 years. People get very distressed and often don't have a clue it's been filled. It can't be valued for what they paid, and they think they've 'saved' by not paying the VAT or customs on it, but just sailed through the airport with it on. I'm not Revenue, obviously, but people need to think if they're really getting a bargain."