Hearts and arrows diamonds explained

Guide

If you are comparing round brilliant diamonds, you will eventually meet the phrase "hearts and arrows", usually attached to a higher price.

Ideal describes a diamond's proportions. Hearts and arrows describes how precisely its individual facets are aligned with each other. They measure two different things, which is why a diamond can be one without being the other.

This guide explains what the designation actually means, how IGI and GCAL document it, and the one thing most articles leave out.

1. Ideal: the proportions

An ideal cut grade is a judgement about geometry. Table size, total depth, crown angle, pavilion angle, girdle thickness.

These numbers set the boundaries of what light can do once it enters the stone. They are necessary, but they are not the whole story, because they describe the overall shape rather than the accuracy of each facet within it.

Two diamonds can sit inside the same proportion ranges and behave differently. If you are new to how cut is graded, our guide to the 4Cs covers where it sits among the four.

2. Hearts and arrows: the precision

IGI describes these as diamonds "cut so precisely that their facet reflections overlap when viewed in a reflective scope."

Look down through the crown and you see eight arrows. Those arrows are the reflections of the eight pavilion main facets, seen through the table and bezels. Turn the stone over and look through the pavilion and you see eight hearts.

IGI is precise about what produces this. The crispness "relies on precise angles in combination with specific facet length, width and azimuth." Angles alone will not do it. Every facet must be the right size, in the right place, at the right rotation.

This is a different measurement from the symmetry grade on a report, which describes the external shape of the stone. Optical symmetry is about how the facets reflect one another inside it.

The technique is not new. Japanese cutters were achieving it in the 1980s using what IGI calls "secret recipes", and the methods had reached cutting houses on several continents by the mid-1990s.

3. What the viewer does, and does not do

A hearts and arrows viewer is a small reflective scope. IGI explains the mechanism plainly. Light entering from above stays white, while light arriving from the sides passes through coloured filament paper, usually red, blue or purple. The result is a structured lighting environment in which the main facet reflections read white against a darker background.

The viewer does not create the pattern. It makes an existing three dimensional alignment visible. If the alignment is not there, no viewer will produce hearts.

Arrows, seen through the crown. Footage credit SamaraJames

Hearts, seen through the pavilion. Footage credit SamaraJames

4. The part most articles leave out

This is the section worth reading twice.

IGI states that "a variety of different standards and definitions exist. Some are stricter than others." There is no single industry wide definition that every seller is held to.

More importantly, IGI notes that "many diamonds produced in modern times show some form of hearts and arrows patterns, simply from good tooling." The institute calls these "happy accident" hearts and arrows, and says they "do not have the distinctive crispness and precision of diamonds purposely produced to top levels of 3D optical precision."

So a photograph of a rough pattern through a viewer proves less than it appears to. Good modern equipment produces something heart shaped fairly often. What separates a deliberate stone from an accidental one is crispness and uniformity across all eight, and that is a judgement better made by a laboratory than by a product page.

5. How IGI records it

Above is a real IGI report from a diamond we handled. Report LG760589357, dated 2 January 2026. A 2.02 carat round brilliant, F colour, VVS2, polish and symmetry both Excellent.

Two lines matter. Cut Grade: IDEAL. And in the comments field, HEARTS & ARROWS.

That is how IGI records the designation on a standard report, as a documented comment sitting alongside the cut grade rather than replacing it. IGI also issues a dedicated Hearts & Arrows Report, which carries the 4Cs, measurements, and authentic images of the crown and pavilion patterns as seen through a viewer.

IGI describes itself as "among the world's only gemological institutes to have established criteria and grading standards" for these diamonds. On a qualifying report, you are looking at the laboratory's photographs rather than the seller's.

6. How GCAL records it

GCAL by Sarine takes a different route. Hearts and arrows is not a separate report but one of eight assessments inside its 8X cut grade, and a stone must earn Excellent in all eight.

GCAL's own figures put the scarcity in proportion. More than half of all round brilliants receive an Excellent cut grade. Fewer than 1% of those qualify as 8X.

The certificate carries the imagery too, the hearts pattern, the arrows, and maps of how the stone handles light.

If you are looking for a stone graded this way, our page on GCAL certified diamonds explains how we source them and how to tell us what you are after.

7. Why it costs more

Footage credit Tracr

IGI answers this directly. Hearts and arrows diamonds do cost more to produce, "primarily due to weight loss incurred in refinement."

Aligning every facet in both angle and orientation takes better tools, more time, and most of all more of the original crystal given away. A cutter working for maximum carat weight will not reach this precision. One working for precision accepts a smaller finished stone.

The payoff, in IGI's words, is "the potential to optimize light performance through cut-consistency, when paired with proper angles for light return", and more perceived dispersion. Note the conditionals. Potential, and paired with. Precision alone does not guarantee performance.

Does everyone need one?

No.

A well chosen ideal cut can be a beautiful diamond, and most people will never look at their ring through a reflective scope. Hearts and arrows suits a particular buyer, the one who values craftsmanship for its own sake and wants documented proof rather than a description.

If that is not you, the same money often buys a larger stone, a higher colour grade, or a more carefully selected one. Our round diamond buyer's guide covers those trade-offs.

In summary

• Ideal describes proportions. Hearts and arrows describes facet precision
• The viewer reveals an alignment, it does not create one
• Good tooling produces rough patterns by accident, so a viewer photo is weak evidence
• IGI records it as a report comment or on a dedicated Hearts & Arrows Report with its own imagery
• GCAL folds it into 8X, one of eight assessments, reached by under 1% of Excellent round brilliants
• The premium is mostly paid in lost carat weight, not in labour alone

A note on what to ask

Ask whether the designation is on the report or only in the description. Ask to see the laboratory's own viewer images. Ask for the crown and pavilion angles anyway, because precision and proportions are separate. And ask whether all eight hearts are uniform, since that is what separates a deliberate pattern from a happy accident.

The report tells you where the numbers landed. Looking at the diamond tells you the rest.

If you would like help reading a hearts and arrows report or comparing two stones, Carateu's concierge is happy to guide you.

Frequently asked questions

Are all hearts and arrows diamonds ideal cut?

IGI describes the precision as "typically associated with Excellent-Ideal cuts of superior quality". The report shown above carries an Ideal cut grade alongside its Hearts & Arrows comment. Because standards vary between laboratories and sellers, check both on the report rather than assuming one from the other.

Does a hearts and arrows diamond sparkle more?

It can, but not automatically. IGI frames the benefit as potential, achieved when the precision is paired with proper angles for light return.

Can I check for hearts and arrows myself?

A viewer will show you a pattern, but judging whether it is genuinely precision cut is harder than it looks, because good tooling produces rough patterns by accident. Laboratory images on a report are more reliable.

Is there one official standard?

No. IGI states that a variety of standards and definitions exist and that some are stricter than others, which is why the issuing laboratory matters as much as the label.

Do lab grown diamonds get these reports?

Yes. Both examples in this guide are laboratory grown, one IGI and one GCAL 8X.

Sources

Every passage in quotation marks above is IGI's or GCAL's own wording, linked at the point it appears. The three pages in full:

• International Gemological Institute, What are Hearts & Arrows diamonds?
• International Gemological Institute, Hearts & Arrows Report
• GCAL by Sarine, GCAL 8X Cut Grade

The IGI report and the GCAL certificate shown in this article can both be checked against the issuing laboratory's own verification page using the numbers printed on them.

Last verified 23 September 2026. Video and stills by Carateu. Additional footage credit SamaraJames and Tracr.