The Girlfriend's Guide to Jewellery
24: Carat 2011-07-22
The last C in the group of ‘Four C’s’ is the carat weight. As we have seen there are 100 points in a carat and one carat equals one fifth of a gram. All gemstones are weighed by the carat, not just diamonds. All other grades being equal, the bigger a diamond is, the more expensive it will be.
Round diamonds of similar weight will have very similar size when cut in accordance with the defined ‘ideal proportions’ for round brilliant cut diamonds.
Gone are the days when round brilliant cut diamonds were cut to any of a wide range of proportions making ‘spread’ stones look large for their weight. A spread stone has a diameter too large for its depth giving it a larger surface and consequently a larger look. Worse yet, a spread cut allows a great deal of light to ‘leak’ out of the stone. This practice was not uncommon in the mid 1900’s and created a situation where some carat stones appeared larger than others giving rise to the idea that there were big carat diamonds and small carat diamonds. That’s just confusing!
What is the best diamond to buy? In short I’d say, buy the biggest most beautiful diamond you can afford. Beauty is in the eye of the beholder and each of us has our own preferences. Your naked eye cannot see the inclusions in VVS, VS or SI 1 clarity diamonds and remember cut and colour have the greatest impact on the beauty of your diamond.
Registration Numbers and Laser Engraving
It is very common these days for a diamond to be accompanied by a grading certificate. A grading certificate grades diamonds in terms of cut, colour and clarity but does not assign value. These certificates are available from the GIA, the AGS and several other independent labs. The ‘cert’, as it is often referred to, may be tied to the diamond by laser engraving the registration number from the cert document onto the girdle of the diamond.
Some cutting factories cutting ideal proportions identify their diamonds with an in-house registration number laser engraved on the girdle of the diamonds they cut. The laser engraving used is tiny, not eye visible and does not affect a diamonds’ cut or clarity grade.
In addition to a grading report registration number there are now Canadian diamonds that have a registration number guaranteeing provenance. Most Canadian diamonds weighing over approximately 0.20 carats have a registration number laser engraved on their girdle indicating that they are Canadian. This registration number is a guarantee of provenance not grade.