Star length is how far the star facets reach from the table edge toward the girdle. It is a percentage of that distance.
In more detail
GIA's Excellent range is 45 to 65% and its Very Good range 40 to 70%. On their own, star and lower half lengths can never take a stone below Good. The T73's stars are at 50%.
On a grading report
On the proportion diagram; GIA reports it to the nearest 5%.
Related terms
- Star facet: Star facets are the 8 small triangular facets of a round brilliant's crown that touch the table.
- Lower half length: Lower half length is how far the lower half facets reach from the girdle toward the culet. It is a percentage of that distance.
- Bezel facet: Bezel facets are the 8 large four-sided facets on the crown of a round brilliant. They run from the table to the girdle.
- Cut grade: The cut grade rates how well a diamond's proportions and finish work, from Excellent to Poor. GIA gives it only to standard round brilliants in the D-to-Z color range.