Tips and Tricks

Pear Brilliant MM to Ct Guide by Rare Carat | Rare Carat

For those of you in the market for a pear shaped diamond but need a little help deciding the size, then this is the right place for you to be! One of the biggest issues with online purchases is sizing. It’s true for clothes, jewelry, and diamonds too. Jewelers use millimeters (mm) to measure the length and width of diamonds. An ideally cut pear diamond will have a mm length and width that directly correlates to its carat (ct) weight. Unlike round brilliants, asscher cuts, and princess cuts (among others), pear cut diamonds are different in the way that their length and width measurement are different. As a general rule of thumb, the length to width ratio for a pear shaped diamond is 1.66 to 1. This ratio can fluctuate up and down, but this is a common middle ground. Anatomy of a pear shape.png

Measuring a Pear Cut Diamond

Pear cuts are measured by length and width. Lengthways is measuring from head (curved bottom) to point of the diamond, whereas width measures from one side of the belly to the other. The diagram above will probably be more helpful with visualizing the parts of a pear cut diamond. Keep in mind that the below chart is based on pear shaped diamonds with ideal cuts, and while these measurements are quite accurate they are not exact, since no two diamonds are the same. Keep in mind that this “difference” I’m mentioning is only about 0.2 mm so it’s safe to say you won’t notice it.

Pro Tip:

While browsing for your perfect diamond keep in mind that pear, marquise, and oval cut diamonds are susceptible to what’s known as the “bow tie” effect. Despite this sounding dapper, it can put quite the damper on a diamond’s appearance. Basically, the diamond wasn’t cut quite right and there is an area that doesn’t return light how it should. This area is noticeably dark compared to the rest of the stone and resembles the shape of a bow tie. While all pear diamonds will have this bow tie effect to some degree it should be subte and not overwhelmingly noticeable.


If you have any questions about how to measure your pear brilliant diamonds, or maybe you want a professional’s advice on what size diamond is right for you, feel free to send one of Rare Carat’s trained gemologists a message via the chat bubble. Happy diamond hunting!

Elizabeth Callnan
Elizabeth Callnan
Elizabeth grew up toddling around in her Grandfather's rock shop which shaped her love and passion for gemstones. Started by her Great Grandfather, she has definitely followed in her family's footsteps. She has recently completed her Graduate Gemologist courses at the GIA and is now working on studying pearls. When she's not adoring the dazzle of gemstones (or writing about them) she's enjoying the captivating beauty of her home state, Hawaii!