Hearts and arrows

Hearts and arrows (H&A) diamonds are precision-cut variations of the traditional 57-faceted round brilliant cut. They are cut to "ideal" proportions with good optical symmetry, polish, and a specific faceting pattern. When these factors are present, the result is a near-perfect pattern of eight symmetrical arrows when viewed from the top (crown) and eight symmetrical hearts when viewed from the bottom (pavilion).

Design factors
The original Hearts and Arrows diamonds appeared in Japan in the mid-1980s. They were cut to "ideal proportions," closely following the guidelines summarized by Marcel Tolkowsky in his 1919 book Diamond Design. These diamonds were cut with very good physical and optical symmetry to achieve an "Excellent" grade in the Japanese laboratory grading system. The faceting scheme involves prescribed lengths and ratios as well as smaller table sizes to produce the distinctive, repeatable Hearts and Arrows pattern.

Less than 1% of the world's diamonds are cut to Hearts and Arrows optical symmetry precision. This is due to the greater amount of rough diamond material that is lost during the additional polishing required to achieve this precise optical symmetry. Diamond polishers may take up to three times longer to cut diamonds to this quality, resulting in a higher waste of the original rough material. Specialized tooling, high-quality cutting wheels, and sometimes 100x magnification are used to ensure careful analysis at every production stage. Consequently, diamonds cut in this manner are more expensive than average cut diamonds.

Viewer
To see the hearts and arrows pattern in a diamond, a specially designed light-directing viewer called a hearts and arrows scope is used. This device allows the viewer to analyze the physical symmetry, contrast, and alignment of the diamond's facets by viewing the stone through both the top (crown) and bottom (pavilion). It directs white and colored light at specific angles to reflect light back from particular facets and angles of the diamond.

Certification and scientific and technical research
In the early 1990s, when hearts and arrows diamonds began to appear in America, this kind of consistent cutting was uncommon, and cut grading did not yet exist in America. The Gemological Institute of America noted several key characteristics in their report: the diamonds were extremely round, with tables measuring 55–57%, girdles that were medium or thin to medium, and excellent grades for polish and symmetry.

The Hoge Raad voor Diamant (HRD) applies objective criteria and uses an automatic measuring device developed in-house to determine whether a diamond meets the H&A standard.

The International Gemological Institute (IGI) is also one of the laboratories that certify Hearts and Arrows diamons.

The Wetenschappelijk Technisch Onderzoeks Centrum voor Diamant (WTOCD) is a scientific and technical research center for diamonds that developed proprietary software to analyze images according to the H&A guidelines set by HRD Antwerp. Based on measurements of the H&A patterns, an expert system evaluates the guidelines to deliver H&A grades.

Diamonds with a hearts and arrows cut command a price premium in the global market, reflecting the greater time needed to produce them, the greater loss of weight from the rough, and their generally better overall cut quality. This cut has also become a popular sales tool in diamond marketing. Although the hearts and arrows pattern indicates a top-tier cut, it does not always guarantee the diamond will be the most brilliant.

Labeling
There is disagreement within the diamond industry regarding which diamonds should be labeled as "hearts and arrows." Historically, the absence of an industry standard meant that different entities could classify a diamond differently—one might designate it as hearts and arrows while another might not. The term "super ideal" is commonly used to describe diamonds exhibiting perfect optical symmetry. Diamonds graded by GIA as "Excellent" in overall cut (with excellent symmetry) or by the American Gem Society as "0" (or "Ideal") typically display some form of hearts and arrows pattern when viewed through a specialized viewer, though the pattern may not be flawless. Many professionals in the industry advocate for grading the hearts and arrows pattern, reserving the label for diamonds that meet stringent criteria. They argue that mere presence of the pattern is insufficient; it must align perfectly with defined guidelines.

Generally, a "hearts and arrows" super-ideal cut diamond is defined by five main components:


 * Pavilion angle range: 40.2–41.6° (optimum 40.6–40.8°)
 * Crown angle range: 32.4–36.4° (optimum 34–35°)
 * Table size range: 53–59% (optimum 55–57%)
 * Lower girdle halves length range: 75–80% (optimum 77%)
 * Star facets length range: 40–55% (optimum 45–50%)

Currently, IGI and HRD grade diamonds for optimal hearts and arrows cut, with IGI issuing specific certificates. GIA, however, does not grade hearts and arrows cuts; instead, a GIA certificate might note "Laser Inscription: H&A," indicating that the term was inscribed on the diamond prior to grading, without implying the presence of hearts and arrows patterns as observed by GIA.

The diamond industry has yet to establish firm criteria for evaluating stones with precise hearts and arrows optical symmetry, lagging somewhat behind the latest technological advancements. For consumers seeking diamonds of this caliber, it is advisable to examine hearts and arrows images through an appropriate viewer.