How to Choose a Trilliant Cut Diamond

trilliant cut diamond

Trilliant Diamond

“Trilliant” is a broad term that’s used to describe cuts based on the shape of a triangle and they are one of the most unique looking fancy shaped diamond in the market.

Typically, the trilliant diamond is cut to equivalent sides and is made up of 50 facets. It is preferred by people who are searching for a fashionable looking stone and want an alternative choice in a market oversaturated with round diamonds. 

In modern times, they are often used in diamond rings as sidestones or as accent stones to complement a main stone instead of a standalone solitaire. Besides applications in ring designs, this versatile diamond cut has also found its use in jewelry bracelets and earrings.

A Brief History And Overview of the Triangular Diamond Cut

Before talking about anything else, we should clarify that if you ever stumble upon the terms “trillion cut” or “trillian cut”, the information you find will actually be related to trilliant cuts. These are just simply “branded” trademarks or some other mistaken names for the original cut.

The trilliant cut was developed during and after World War II, but it was only patented in 1962 by the Henry Meyer Diamond Company. Once the patent has expired, the cut technique became freely usable to all diamond cutters around the globe.

The cut can be presented as transitions between different types of diamond shapes. The most common description usually states that it is a triangular radiant cut without the corners cut off. It has a number of variations depending on how the cutter decides to fashion the stone. In most cases it features 31 or 50 faces – that is, the latter can be considered a full cut brilliant.

The Trilliant Cut Was Developed to Get Better Yield From Rough Stones

macle rough diamond

Flat, Twinned Diamond Rough (Macle)

Trilliant cuts typically have shallow depths and this is largely due to the nature of the rough being used. In shaping trilliants, triangular shaped roughs called macles are usually used in order to maximize carat weight retention.

As you can see from the example above, the overall shape and outline of the macle makes it a perfect candidate to achieving a trilliant. In today’s market, the terms triangular brilliant and triangular modified brilliant are used by GIA in their lab reports to describe unbranded triangle shaped diamonds.

Tips to Selecting a Nice Modified Triangular Brilliant Cut

comparing a round brilliant cut against a trilliant cut diamondTrilliant cut diamonds look larger than other shapes for their carat weight because they are cut to shallower depths of around 35 – 46%. While this is an intrinsic property of trilliant diamonds that makes it look bigger, a shallow depth will also result in lesser brilliance and fire.

More importantly, when a shallow cut diamond is dirty, it can accentuate any imperfections within the stone due to the loss of brilliance. As a guideline, I recommend buying trilliants with at least an SI1 clarity.

Note: Trilliant cut diamonds with a depth ratio of less than 35% are often used as side-stones in a ring. If you are choosing a diamond for a solitaire setting, choose a diamond with a depth in the higher limit of 44+ % to get better fire and brilliance.

Like the marquise and heart shaped diamonds, trilliants also have pointed corners which requires extra care to prevent chipping or breakage. Because of this, it is advisable to set them in V-shaped prongs or mountings that provide adequate protection to the sharp corners.

Recommended Proportions For Trilliant Diamonds

Compared to the other fancy cut diamond shapes, the symmetry, polishing and proportions of the trilliant diamond will significantly impact how its visual appearance. I recommend a minimum of “very good” ratings for both polish and symmetry.

Excellent Very Good Good Fair/Poor
Table % 56% – 66% 54% – 68% 52% – 70% Outside Ranges
Depth % 35% – 46% 34% – 48% 33% – 52% Outside Ranges
Polish/Symmetry Excellent – Very Good Good Outside Ranges
Length to Width 1.00 0.95 – 1.05 1.10 – 1.20 Outside Ranges
Girdle Thickness V. Thin – Slightly Thick V. Thin – Thick Outside Ranges
Culet Size None Very Small Small Outside Ranges

* Note: This table should be used as a reference only. Due to the varying length/width ratio that a diamond may be cut to, there are no hard and fast rules for choosing a diamond based on proportions alone. I don’t recommend buying blind and you should always request for additional information like an ASET image or a photograph/video of the diamond.

Pay Attention to Length-to-Width Ratios

A trilliant diamond looks best when it is in the form of an equilateral triangle. Ideally speaking, a 1:1:1 proportion on each side of the diamond is the best. An irregular or out-of-symmetry diamond will be very obvious to the eye and should be avoided.

length to width ratio of trilliant cut diamonds

For Solitaires Or Main Stones in a Ring

If you are in the browsing stage of choosing a solitaire diamond, you might want to consider visiting They hold a sizable inventory which is readily accessible to consumers and offer GIA certified diamonds.


Click this link to visit…
Once you are there, filter diamonds by “certificate” and buy only GIA graded diamonds.

Alternatively, I recommend Whiteflash’s custom design where they can source for a great looking stone on your behalf and get it set in a ring of your choice.

whiteflash custom design

Get more details on this ring by clicking on this link

For People Looking for Settings Utilizing Trilliant Sidestones

You might want to check out for great looking designs. My favorite is the one on the left with the engravings as it gives the ring an authentic Victorian look.



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