How do you know if the diamond you are considering has a good spread? If you divide the depth by the diameter and multiply by 100 you can calculate the depth percentage. This should be between 56% and 65%. If the table is small the depth will can be larger, and vice a versa. The smaller the depth percentage, the larger the spread. Other factors that effect spread are the girdle thickness and crown and pavilion angles.
Holloway Cut Adviser rates a diamonds spread.
This stone has table and depth proportions of 60:60. Normally you would expect a 6.5mm spread for a 1.00ct stone. This one spreads 8% less at 6.3mm because it has a thick girdle.
Uper 1/2 carat has the same spread as lower lifeless 2/3 carat