The Process
The process of cutting an artistic gemstone is done in stages across many hours. It is a labour of love, patience and obsessive attention to detail.
Assessment - The inner beauty
The first stage in cutting a gem involves assessing the rough material. Correct assessment of the rough is the most vital step to creating a beautiful finished gem and takes years of practice to refine. We must closely inspect the rough piece from all angles, in differing light and shadow. We are initially looking for structural faults such as cracks and cavities to determine whether the rough will hold up to cutting. To hit an open cleavage plane or deep crack when cutting a stone usually results in the material shattering or splitting.
If the stone has too many substantial flaws, we will not cut it. Cracks and inclusions limited to one part of the stone, or on the edges can be cut away and result in a smaller finished stone.
As gem artists we look for and weigh the physical characteristics of the stone - size, inclusions and their location, colour zoning, play of colour, pleochroism, cleavage planes, the shape and more. These characteristics give us clues as to how the beauty hidden within the material can be made to shine and what designs can best achieve this. Based on these observations, the gem artist decides which direction of the stone is best facing up, what potential shapes will suit the rough and what excess areas of the stone will need to be ground away.
2. Refinement - The vision of beauty
In the 2nd stage of gem cutting, we are refining the vision for the finished gem. The material is roughly sanded back to remove any pits, projections and near surface reaching inclusions, as planned in stage 1. The stone is now close to its final outer shape and re-measured. If a specific design has not yet been chosen, now is the time. There are literally thousands of designs - how could we ever choose? We take the information gleaned from step 1, crunch some numbers, and compare these to ratios of designs specifically chosen to bring out the best qualities of the material. Sometimes, a piece of rough just inspires a particular design.
For example in the photo is a wide and long but very thin pyrope garnet of the most delicious cherry red colour. The artist decided that a faceted crown and flat bottom was in order; but what shape? As is, the rough implies a rectangle, but the gem needed something a little more lively. An oval design called Pineapple was chosen for its series of diamond shaped faces on the crown.
After the design is chosen, the stone is affixed onto a brass rod called a dop stick in preparation for cutting.
3. Destruction - beauty un-made
In this stage the initial beauty of the rough gem must be un-made before the artistic vision can be realised. Gem cutting is largely not cutting at all, it is sanding and grinding using diamond grits. With grinding wheels or metal discs called laps we sand away a continuous perfect curve or a series of geometric faces. In cabochon cutting, the gem artist steadily orients the stone free hand to each of 6 cab cutting wheels. The material is rotated and the elegant rounded curve is slowly brought forth. In faceting, we use a machine which allows us to set precise angles and rotate the stone in an index to stop on a specifically oriented spot before applying the stone to the lap and sanding a face. Some designs contain hundreds of faces.
Cutting begins with a rough diamond grit, all faces or surfaces are sanded in and shaped on one half of the gem. Then a finer sanding grit is applied to all faces or surfaces to remove the very rough previous scratches, refine the orientation of faces or sculpt the elegant dome. The exterior of the gem rough is destroyed. It is frosty, scratched, nearly unrecognisable until….
4. Pre-Polish - evolving beauty
This step is the favourite of many an artist. The distinction between a sanded area and a pre-polished area immediately builds excitement. This stage is vital for achieving good meet points and an excellent polish. All previous scratches and damage must be removed or a pristine polish will not occur. We use either 8000 or 14,000 diamond grit as a pre-polish. Many overseas cutting houses leave their finish at this stage. Artists at The Gemstone Gallery do not. So much work has gone in to mining the gem, transporting the rough, and the cutting stages already undergone; this beautiful little slice of history deserves more. We take the stone one step further.
5. Polish - beauty realised
Polishing is the final stage. A well polished gemstone is a true masterpiece. It is so exciting to see multiple light flashes dancing across the magnifier we wear as the polishing progresses! There are 2 basic categories of polishing mediums - diamond polish and oxide polish. Diamond polishes remove all of the previous scratches but with particle size so tiny that the eye sees a high lustre mirror like finish. Researchers assume that oxide polishes create a chemical as well as mechanical reaction with the surface of some materials. This oxide induced reaction produces what is called the “Bielby layer” which also delivers a high lustre polished surface. Diamond is our preferred polish, however some materials, indeed some odd faces on a single stone, require a different approach.
Gem art created with The Gemstone Gallery truly adds to the beauty of the world and the beauty of your story for years to come.
Tell us about your dream gemstone. Let’s make it happen.