Bow Tie Effect
The bow tie effect refers to dark regions found on some diamonds in the shape of a bow tie.
The bow tie effect only affects marquise, oval, pear and sometimes heart shaped diamonds and runs along the width of the diamond in the centre of the diamond.
Bow Tie Effect and Proportions
Whilst even a small bow tie effect is rarely avoidable, a better proportioned diamond will give less of a bow tie effect than a poorly proportioned one. Listed below are links to proportions that minimise the bow tie effect:
Diamonds With No Bow Tie Effect
United Diamonds explains:
Diamond Grading Certificates and The Bow Tie Effect
Grading certificates will not comment on any bow tie effect. Therefore, it is beneficial to either view the diamond in person, or at least a photo before purchasing it.
Bow Tie Effect (diamondmadeeasy.com)