This article discusses prong setting techniques for diamonds as part of a series of discussions on an array of different setting techniques used for colored diamond engagement rings. The descriptions are useful in understanding the pros and cons of specific techniques, and communicating with your jeweler, when buying or ordering a custom made engagement ring.
What is prong (Claw setting)?
Prong setting (also known as claw setting in the UK), is probably the most common technique used for setting diamonds. The post sits to the side of the diamond adjacent to the diamonds girdle. A groove is cut into a metal post and the top part of the post is pushed over the top of the stone. The prong is trimmed and either rounded off or fashioned to a shape such as a Tiger Claw (See below). A single prong is relatively minimalistic in securing the diamond and will maximize the look of the stone, however it has its limitation when trying to set larger diamonds over 1.50Ct. The thickness of the metal post used should be proportionate to the diamond being set. The metal shouldn't dominate the stone and the prongs shouldn't be too weak to support the stone. It is also relevant as to how many prongs are used. The more prongs the greater the security, however the more diamond is covered.
For larger diamonds over 1.50Ct, where the style of the engagement ring warrants a prong; it is worth considering setting with a double prong. That is two posts adjacent to each other. Both prongs are used to set the stone. In many cases four double prongs are used for each center diamond being set. Each prong can be of a smaller gauge i.e. doesn't need to be so thick, and is actually less conspicuous then a single thick prong.
Half Split Double Prongs
A similar technique to double prongs is a 'half split double prong'. The prong usually graduates in size from being narrow at the bottom and wider at the top. About half way up the prong begins to split to two. The stone is finally set with two adjacent narrow prongs, with usually four half split double prongs for each center diamond being set.
For diamonds of a square nature with cut corners such as a Radiant cut or Emerald cut, where four prongs are used in the corners for setting the stone, a flat prong can be used. The prong is usually slightly wider then a rounded prong. The setting principal is similar in nature, however the prong covers a wider area and is relatively more secure and suited to a diamond of this nature.
A variation of the rounded single prong is a Tiger Claw prong or Eagle Claw. Once the diamond is set and the prong is trimmed, the setter will fashion the top of the prong into the shape of a claw. This is one of my favorite styles as it ads an esthetically pleasing look to the prong and shows care has gone into the final touches of the engagement ring. It's actually more expensive as the setter needs to take time to carefully file down each claw in proportion to the stone.
For diamonds that have a sharp corner to them, such as a Marquise, Pear shape or Heart shape, a V prong is useful. As the name describes, the prong is shaped as a V and envelopes the corner point of the diamond. It is more secure for setting diamonds of this nature. However it should be a proportionate size and fashioned slightly after setting, so that it covers enough of the stone, but not too much that it interferes with the overall look of the stone.
Another alternative to the V prong for setting corners is a regular round prong, however the groove in the prong where the corner of the stone sits, should run along the prong on the inside and not across the prong, preventing the stone from coming loose and escaping.
For Princess cuts, Large Carres, or variants of a Radiant that have a square cut, a Corner prong is used. Similar to a V prong, the perpendicular sides envelope the corner of the diamond and holds it in place. A minimum of four prongs are required. Care should be taken to ensure that each wall of the corner prong is finished evenly and covers the stone securely, however as unobtrusively as possible without dominating the stone.
In places where there are diamonds that sit adjacent to one another, such as halos or eternity bands, a shared prong can be used. The shared prong sits at the juncture of the girdles where two stones meet, usually a round diamond or princess or Carre. For a round diamond, the prong is grooved on two sides of the prong, or the prong is split to two and used to set two stones. For a princess cut, the prong sits at the corner of the stone, extending out to cover two stones, side by side.
Points to look out for
General points to look out for are prong size. Making sure the prong is not to thick or thin, that it is proportionate in size to the stone. A major issue is that the prong is securely and cleanly cupping the stone, so that there is less chance of it coming loose and falling out. The prong style used should be in keeping with the diamond being set and the overall look of the ring.