How Gemstone Sizes Affect Custom Jewelry

Gemstones Amethyst

If you’re purchasing a precious gemstone, you’ll quickly learn that its size is determined by the weight or carat value. If you haven’t used a gemstone size chart before, you may wonder why they’re so important.

What Are Calibrated Gemstones?

Calibrated gemstones are standard sizes and cuts that fit the regular settings used in most mass-produced jewelry. In fact, these stones make mass-produced jewelry possible because manufacturers can produce hundreds – even thousands – of identical jewelry items easily and efficiently.

When replacing lost or damaged gemstones for an existing setting, a jeweler can simply choose calibrated gems that fit the setting, then reset the jewelry item. They only need to consult the gemstone size chart to get this information. 

Do Unusual Gemstone Sizes Affect Jewelry Pieces?

There are times when large and/or valuable gemstones cannot be cut to a standard size without reducing their value. Professional gemstone cutters focus on enhancing the individual stone (which may result in an unusual size or shape).
The jeweler who sets an irregularly-sized stone must custom-design a setting. Not only will this setting hold the stone in place, but it will also enhance its unique qualities.

Do Calibrated Gemstones Need to Match Standard Settings Perfectly?

A precious stone doesn’t need to be precisely the same size of the jewelry setting.
A skilled goldsmith will be able to alter a standard setting to accommodate a variety of shapes and sizes.
For example, round solitaires can be placed in standard settings. Factors like gemstone hardness, daily use, and size need to be taken into consideration for other stone cuts (e.g. marquise, emerald).

How to Design Bespoke Jewelry for a Gemstone

If you are commissioning a bespoke piece of jewelry, you can choose any stone you desire. If you later want to replace a gemstone in your setting, it may not require a new setting size. Depending on your stone’s size and shape, goldsmiths are typically able to make setting adjustments of 0.2mm or more.

Gemstone Size Chart for Specific Gems

It’s unlikely that you’ll know the size of gemstones simply by looking at gemstone weights. After all, the density (or specific gravity) of a diamond will differ from that of a sapphire or an opal. For example, a 6.5mm round diamond, sapphire, and opal all have different carat weights.
Therefore, a gem weight chart alone cannot tell you the size of a gemstone. You need to know the type of stone as well as the size in millimeters.

How Gemstone Size Varies Between Stones

Size (round stone)DiamondSapphireOpal
6.5mm1 carat1.14 carat0.61 carat

Some gemstone charts combine both carat and size. That’s why it’s possible to use separate sapphire, ruby, or diamond carat size charts to determine the exact size of the gemstone and its carat value.

Gemstone Size Chart PDF

From emerald to oval marquise cuts, click on the link below to view the gemstone size chart for the most popular stones, sizes, and cuts.

Round Faceted Gemstones Size Chart and Weight Chart

How to Use the Gemstone Size Chart to Create Bespoke Jewelry

For bespoke jewelry designers like Jaume Labro, it’s possible to incorporate any gemstone sizes into a design. However, to get a better idea of how your gemstone will appear, you’ll first want to know the size. For example, a 2-carat sapphire is denser than a 2-carat diamond (and will therefore be smaller).
Size is important in determining the final design of your fine jewelry ring, but there are other elements –  like the four Cs of diamonds – to take into consideration. While it’s useful to know the way diamonds are measured and priced, their value, however, is intricately connected with a priceless precious memory.

How to Choose the Perfect Conflict-Free Gemstone

Labro offers a magnificent range of ethical diamonds, sapphires, and other precious gemstones that are tracked directly from their source. If you would like assistance in choosing precious stones – or selecting a jewelry design to match your desired stones, please don’t hesitate to contact us. Our expert gemologists, goldsmiths, and jewelry designers are at your service.