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Cutting and polishing are where knowledge of a mineral's properties is put into practice. Hardness that varies with direction, cleavage, and pleochroism all influence how a crystal should be oriented and worked.
We document technique alongside results, so that observations made at the wheel can be related to the properties measured in the laboratory.
Rough is examined for optic axis, colour zoning and cleavage directions before any cutting begins.
Placing the table for best colour in pleochroic stones such as sapphire and tanzanite.
Improves face-up colour and reduces the risk of damage during cutting.
Different abrasive grades and lap materials are compared on the same species under controlled conditions.
Finding reliable polishing combinations for stones that are difficult to finish.
Sharper facet junctions and a cleaner surface polish.
Polished facets are inspected under magnification and reflected light for scratches, pits and polish lines.
Assessing finish quality and diagnosing the cause of surface defects.
Feeds directly back into improved technique.
Many gem minerals show different colours or different hardness in different directions, so the same crystal can give very different results depending on how it is placed.
Stones with strong directional hardness or perfect cleavage, such as kyanite or tanzanite, need the most care.
Yes. Understanding how a stone was cut helps in judging its quality and in caring for it properly.
Establishing species and variety through optical, physical and spectroscopic measurement.
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Consistent description of colour, clarity, cut and weight under controlled conditions.
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Locating and modelling internal features in rough and polished stones.
Read MoreAdvancing the understanding of gemstones through science, precision and innovation, from their formation deep within the Earth to the finished stone.
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