The bow-tie effect

A bow-tie is a dark band across the belly of an oval, pear or marquise. These pages test it on two marquises with the same outline and facets: DG-Bowtie, which has a band, and our Marquise, which doesn't. We use the light map of our 3D Gemstone Simulator, Brightness & Tilt Analysis and the Cut Performance Wheel to test four published explanations, then fix one stone and give you a routine to check any other.

New here? Start with Fixing a bow-tie: the steep belly of DG-Bowtie.

1. 10 s

   1 · Video

   The bow-tie effect in diamonds: what it is

   What a bow-tie is, the parts of an elongated stone, and how to read the four colors of our light map.

2. 2 · Article

   Which diamond shapes get a bow-tie: oval, pear, marquise and more

   Four published lists of bow-tie shapes, the criterion behind them, and why the marquise is hardest but not doomed.

3. 10 s

   3 · Video

   Bow-tie in the stone, sometimes on your finger: tilt and head shadow

   Why the same stone shows a bow-tie in one room and not in another, and what tilt and your head's shadow do.

4. 4 · Article

   What causes a bow-tie? Four explanations, tested

   GIA, the NDC, Estate Diamond Jewelry and Ritani explain the bow-tie in different ways. We test each on the light map.

5. 5 · Article

   Is a bow-tie always there? How much is normal

   Some bow-tie is "always present", sources say. One counterexample, stress-tested in every room, head shadow and tilt.

6. 6 · Article

   Bow-ties and grading reports: what the numbers can't tell you

   What the report, the finish grades, the ratio and the depth can and can't tell you about a bow-tie.

7. 7 · Article

   Why bow-ties are still cut: weight, outline and cost

   The weight trade-off behind a deep-bellied bow-tie: the same carats for less face-up size.

8. 1 min 29 s

   8 · Animated explainer

   Fixing a bow-tie: the steep belly of DG-Bowtie

   The diagnosis and rebuild of a real marquise: the 51.9° belly limit, the result in every tool, and what the fix cost.

9. 9 · Article

   How to check a stone for a bow-tie: a bench routine

   A routine to check any elongated stone for a bow-tie, from a dim room to its cutting file.

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