Fancy Shape Cut Grades
This is another important consumer point.
GIA provides an overall Cut grade for standard round brilliant diamonds, but fancy shapes such as oval, pear, cushion, emerald, and radiant are evaluated differently and do not simply receive the same overall GIA cut grade framework used for rounds.
That makes visual evaluation even more important.
For fancy shapes we look closely at:
- Proportions
- Face-up spread
- Symmetry
- Bow tie
- Light return
- Shape outline
- Length-to-width ratio
- Windowing
- Facet pattern
- Overall beauty
Sometimes a diamond that looks mediocre on paper looks beautiful in person.
Sometimes the opposite is true.
Length-to-Width Ratio
Length-to-width ratio measures how elongated a diamond appears.
You calculate it by dividing:
Length ÷ Width
A 10.0 × 7.0 mm oval has a ratio of approximately 1.43.
Ratio is largely a matter of taste.
Two people can look at the same shape and prefer entirely different proportions.
That is why we try not to tell customers that there is one perfect oval, pear, radiant, or emerald shape.
There is only the proportion that looks best to you.
Polish and Symmetry
These appear separately on grading reports.
Polish
Polish refers to the quality of the finished facet surfaces.
Symmetry
Symmetry refers to how precisely the facets align and relate to one another.
Excellent polish and symmetry are desirable, but they should be considered alongside the diamond’s overall appearance rather than treated in isolation.
Fluorescence
Diamond fluorescence refers to the visible light some diamonds emit when exposed to ultraviolet radiation.
It is usually described on grading reports as:
- None
- Faint
- Medium
- Strong
- Very Strong
Fluorescence is not automatically good or bad.
In some diamonds it has little noticeable effect in normal viewing conditions.
In others, particularly certain lower-color stones, blue fluorescence may visually counter some warmth.
Rarely, very strong fluorescence may contribute to a hazy or oily appearance.
Again, the actual diamond matters more than a single line on the grading report.
Certification and Diamond Grading Reports
A grading report provides an independent evaluation of the diamond.
For important natural diamonds, GIA remains one of the most recognized grading laboratories in the world.
A GIA Natural Diamond Grading Report can include:
- Shape and cutting style
- Measurements
- Carat weight
- Color
- Clarity
- Cut grade where applicable
- Polish
- Symmetry
- Fluorescence
- Proportions
- Inclusion plot
- Treatments when detected
GIA also offers different natural-diamond report formats depending on stone size and service type.
A report is extremely useful.
But a report does not replace your eyes.