Buying a Trillion-Cut Diamond

A trillion-cut diamond makes a distinctive center stone, but finding a good one can be difficult. Learn how to choose the best quality stone for your ring.

5 Minute Read

HomeDiamond AdviceDiamond ShapesBuying a Trillion-Cut Diamond

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If you're looking for a diamond that will stand out from the crowd, a trillion shape could be a great option for you. Also called trilliant or triangle diamonds, these stones have a large face-up size and attractive prices. However, there's a catch. Finding one can be very difficult, let alone a good-quality center stone. Learn whether this shape is right for your ring and how to judge a trillion-cut diamond.
A trillion-cut diamond adds a distinctive geometry to any ring. © CustomMade. Used with permission.
Find this Ring
at CustomMade

Working with a custom jeweler like CustomMade will help you find the perfect trillion to feature in your ring. Plus, the ring will be custom-fit to your diamond, so there's no headaches when setting the stone.

The Pros and Cons of a Trillion-Cut Diamond

Every diamond shape has its benefits and drawbacks. Ultimately, you should get the diamond shape that works best for your style.

Pros: Size, Cost, and Style

There are plenty of good reasons to get a trillion-cut diamond. Did you know that a trillion-cut diamond will look larger than a round with the same carat weight? In fact, it doesn't just look larger, it actually has a surface about 12% bigger. A trillion has the largest face-up area of any diamond shape, except a marquise.

0.34ct trillion
At 0.34 cts, this center stone has a face-up size comparable to that of a 0.5-ct round. You can also find something similar at CustomMade. Photo courtesy of Apple Tree Auction Center and

A trillion will also cost much less than a round of the same weight. Round diamonds sell at a premium due to high demand. So, choosing any fancy shape — any finished shape other than round — can save you some money.

Finally, you'll rarely see trillions as center stones, so your ring is sure to be an eye-catcher. If you have eclectic tastes, there's no better reason to buy a trillion-cut diamond. The sharp points and steep angles also make this shape a great option for a modern look.

trillion style
Trillion-cut diamonds make a bold statement. You can find a similar ring at CustomMade. Photo courtesy of Freeman's and

Cons: Fragile Corners, Hard to Find

The trillion does have some physical weaknesses. Although diamonds are famously resistant to scratching, the sharp corners of a trillion-cut diamond are likely to chip and break. Make sure to have the stone placed in a protective setting, such as V-shaped prongs or a bezel.

bezel set trillion engagement ring
Although prongs will protect the diamond well enough, a bezel setting provides more security (and won't snag on clothing). Find a ring like this at CustomMade. Photo courtesy of Ewbank's and

Perhaps the most significant drawback to choosing a trillion is limited availability. Major retailers like James Allen or Blue Nile don't carry trillion-cut diamonds. Instead, try working with a custom jeweler like CustomMade. They can source the perfect trillion-cut diamond for your ring.

Judging Trillion Quality

Unlike round diamonds, trillions don't have any specific guidelines for good cut quality. Instead, you'll just have to shop around for a trillion that looks good. If you're buying online, that means you'll have to find a vendor that provides good pictures and videos of your diamond. If you're shopping at a brick-and-mortar store, make sure the merchant shows you your diamond from all angles.


Limit your search to certain proportions. Make sure the total depth percentage is between 32 and 48% to prevent light leakage. Limit the table width to 50 to 70% of the diamond width, too. Finally, you'll want a length-to-width ratio of 1.0 to 1.1 to avoid an off-shape trillion.

odd proportions
This trillion has a very odd shape. You can also find something similar at CustomMade. Photo courtesy of DuMouchelles and

Shape Appeal

Symmetry is essential to shape appeal, but it's not the only important aspect. You should consider the type of trillion shape you want for your ring.

Flat or Rounded Sides?

Do you want flat sides or rounded sides? Flat sides will give your ring a strong geometric look, while rounded trillions are generally preferred for a diamond center stone. Rounding can also be slight or prominent, whatever fits your style.

shape appeal
With great proportions and rounded edges, this center stone has amazing shape appeal. Find a similar ring at CustomMade. Photo courtesy of 21st Century Auctions and
Sharp Corners?

Consider the type of corners you'd prefer, too. Most trillions have sharp corners that are susceptible to damage. On the other hand, some have cut-off corners that are less likely to break. However, these will give the diamond a different look.

sharp geometry
The sharp corners in this trillion-cut diamond pair with princess-cut side stones for a dramatically geometric look. Design your own ring like this at CustomMade. Photo courtesy of Wickliff & Associates Auctioneers and
Look for Symmetry

Next, look for symmetry. Trillions should be equilateral triangles, so all three angles should be equal and all three sides should have the same length.

uneven sides
The sides of this trillion-cut diamond appear to have unequal lengths. You can also find something similar at CustomMade. Photo courtesy of Alex Cooper and

The back facets should provide light return in a symmetrical fashion, too. If one area is more sparkly than another, this indicates poor cut quality.

Rounded sides should be equally round and without bulges.

Clarity for a Trillion Diamond

Since trillions are a brilliant cut, they should hide inclusions well. An SI clarity trillion will very likely appear eye-clean when set in a ring.

si2 clarity trillion-cut diamond
Just because this diamond has an SI2 clarity doesn't mean it looks bad. Find a similar ring at CustomMade. Photo courtesy of 1 Great Deal Auctions and

That said, since a well-cut trillion is so hard to find, we recommend keeping your search as open as possible. Consider every clarity grade from SI2 and up, so you can find a diamond with good shape appeal and top sparkle.

Color in a Trillion Diamond

Like clarity, color is a secondary concern. Ultimately, you just want the diamond to look white in your ring. Jewelry metals can have a major effect on what a diamond's color looks like in its setting. So, for white gold and platinum settings, stick to a diamond color grade of H or better. In yellow gold or rose gold settings, a color grade of J or better will look beautiful.

j color trilliant diamond
J color can still look good in white gold. You can also find a similar ring at CustomMade. Photo courtesy of Jasper52 and

Where Can I Buy a Trillion-Cut Diamond?

Since most retailers don't carry trillion-cut diamonds, it's best to work with a custom jeweler. CustomMade is an online jeweler that creates jewelry tailored to your style and budget. Their experience can point you towards a great trillion diamond.

A custom jeweler will do the hard work of sourcing your diamond. © CustomMade. Used with permission.
Find this Ring
at CustomMade

Addison Rice

A geologist, environmental engineer and Caltech graduate, Addison’s interest in the mesmerizing and beautiful results of earth’s geological processes began in her elementary school’s environmental club. When she isn’t writing about gems and minerals, Addison spends winters studying ancient climates in Iceland and summers hiking the Colorado Rockies.

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