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The term carat is also often misunderstood. It refers to how much a gemstone weighs – not it’s size. Thus, diamond carat refers to the weight of the diamond stone (or its apparent size).

Carat is the standard measurement metric for gemstones and precious stones, particularly diamonds. A metric ‘carat’ is defined as 200 milligrams with each milligram sub-divided into 100 ‘points’. This allows precise measurements to the 100th decimal place.

In industry lingo, jewellers and gemmologist may refer to gemstones by the points of their carat weight. For instance a 0.5 carat gemstone may be referred to by a jeweller as a “fifty pointer”.

All other diamond attributes being equal, a diamond’s price will increase with increased carat weight since larger diamonds are harder to come by. Make sure to pay particular attention to the diamond’s cut, since a high carat weight diamond that is poorly cut may look smaller in comparison to a smaller carat weight diamond that is better cut.

Some diamonds are considered magic sizes. Half carat, three-quarter carat and single carat diamonds are such examples. To maximise value of your diamond purchase, consider purchasing a diamond ever-slightly below these magic sizes. The outcome will be visually negligible to the naked eye, but potentially save you big on cost.

Some settings can also make a diamond appear bigger than they actually are. Halo settings, for example, creates a ring of small diamonds around the centrepiece diamond, giving the appearance that the main diamond is larger than it actually is.

Finally, fancy shaped diamonds may appear larger than their actual carat weight. Shapes like oval, pear or heart diamonds may be worth considering when trying to get the greatest bang-for-your-buck when it comes to carat weight.

Origin of the Carat System

In order to understand what a diamond carat measures, it is important to know the origin of the modern day carat system.

The cart weight system started with carob seeds, when early gem traders used the small, uniform seeds, which functioned as counter weights in their balance scales. Today, the carat weighs the same milligram weight all around the world.