A 7.41 carat oval blue Zircon is next to a 7.41ct oval Aquamarine on a purple background. Even though they are the same carat weight, because of the differences in density, the Aquamarine appears much larger.

Why Carat Weight Doesn’t Tell the Whole Story

Header Image: A 7.4 carat Zircon next to a 7.4 carat Aquamarine which appears much larger due to their different densities.

One common misconception when it comes to choosing a gemstone is equating carat weight with the physical size of a gemstone. We don’t blame you! Everyone knows Diamonds’ 4 Cs – colour, carat, cut and clarity. That’s where this misconception usually comes in. Modern diamonds are all cut in the same proportions to maximise sparkle, which is highly dependent on how the angles match up to disperse light. So, one 4 carat round brilliant would be nearly identical to another 4 carat round brilliant! Coloured gems, on the other hand, are cut to maximise colour and character which means that our skilled lapidarists will study every piece of rough to coax out its greatest potential. For example, bi-colour gems are cut to showcase the interplay of colours in the most striking manner!

A 7.5 carat Watermelon Tourmaline shows a unique gradient of colours from pink to white to green and was specially cut to bring out these hues.
Check out the beautiful gradient of pink to white to green on this over 7 carat step-cut Watermelon Tourmaline!

Carats are a measure of a gem’s weight, not its size. Gemstones with the same carat weight can appear drastically different due to variations in density and cut. And density, or how ‘tightly packed’ a material is, varies among gemstones. For example, side-by-side, a one carat Tanzanite will visually look larger than a one carat Sapphire due to the former’s lower density.

Moreover, the cut of a gemstone significantly influences its appearance. That’s why a well-cut gemstone is so important, and the most skilled gem cutters will be able to shape and facet stones to enhance their natural beauty.

A trillion cut pink Gemstone in one of our Signature MADLY designs, set in 18K gold and Diamonds.
A trillion cut pink Gemstone in one of our Signature MADLY designs, set in 18K gold and Diamonds.

The choice between a shallow or deep cut can significantly impact the way light interacts with the gem, and this affects both colour and brilliance. A shallow cut gives the illusion of a much larger gemstone, and in overly dark gemstones, can bring more life and light through. Other gems are cut deeper in order to coax out the most saturated colour, but this may mean that a 3 carat Sapphire might appear to be the same face-up size as a 2 carat Sapphire. 

The balance between these factors is an art, and skilled gem cutters use their expertise to find the perfect equilibrium. As coloured gem specialists at MADLY, these factors are also considered in our pricing so don’t worry about getting ‘bang for your buck’! Trust your eyes and go with that gut instinct that connects you with the right gem!

A nicely proportioned, almost 8 carat deep red cushion-cut Garnet is place on an orange background with a pink flower on the side white the tips of the model's fingers are there to show relative size.
A nicely proportioned, almost 8 carat deep red cushion-cut Garnet.