The effects of incorrect cutting angles and facet placement on brilliance and dispersion

horrible cutting jobs

Warning – examples illustrated represent extreme variations fashioned to accentuate the described effects
Incorrect angles and misaligned facets are usually conscious actions taken by the diamond cutter to maximise the return on a given piece of rough gem material. You will probably never see stones showing these problems to the extent of those illustrated above and certainly not in flawless 1 ct diamonds

All stones shown in this picture are 6 m.m. cubic zirconia.
Skewed

This stone is cut from wedge shaped rough, with an off set culet and table, a slightly larger and heavier stone can be salvaged from this awkward shape. The pavilion angles will vary from too low on the long side and too steep on the narrow side, the crown angle variations are similar. internal reflection suffers considerably.

 Bad Meets

This stone has facets that are neither symmetrical nor opposite in placement, they vary in shape as well as size. Overcutting and offset or double/split facets are sometimes used to remove a surface flaw that would otherwise detract from a finished stone. Stones cut this badly are usually very small.

 Too Shallow

Sometimes referred to as swindled this stone’s weight is much less than the optimal cut stone. Faced with a very thin rough a zealous, or threatened cutter can still attempt to cut a big stone. All pavilion facets are below the critical angle causing a washed out dead stone, This effect can be reduced by cutting a small table.

 Too Deep

Faced with the extreme chore of excess material removal and having a piece of rough not quite big enough to saw, a cutter can save time and boost a parcel weight with heavy stones. All pavilion facets are cut too far above the optimum angle producing a deep stone that traps the light rather than returning it to the eye