5 diamond myths Reddit keeps getting wrong

Short answer: online forums give a lot of good diamond advice, but five ideas get repeated so often that they turn into rules: that any fluorescence is bad, that a full 1.00 carat is the smart buy, that identical grades mean identical stones, that lab-grown diamonds are either fake or worth the same as natural, and that every grading lab is equivalent. Each one has some truth in it and an important exception.

I'm a GIA Graduate Gemologist. Here's how I'd correct each one when I review a buyer's quotes.

Myth 1: "Fluorescence is always bad"

Fluorescence is a glow some diamonds show under ultraviolet light. In a small share of stones, strong fluorescence can make the diamond look slightly hazy. In most stones it has no visible effect in normal light, and diamonds with fluorescence often cost less than the same grades without it.

What to do: don't rule it out on paper. If a stone has medium or strong fluorescence, look at it (or a video of it) in daylight and ask the jeweler about transparency.

Myth 2: "Always buy a full 1.00 carat"

Prices tend to jump at round weights like 1.00, 1.50 and 2.00 carats, because demand concentrates there. A stone just under the mark, such as 0.90 to 0.99 carats, can look almost the same size on the finger and cost noticeably less.

What to do: compare face-up measurements (the diameter in millimeters), not only carat weight. A well-cut 0.95 can face up as large as a poorly cut 1.00.

Myth 3: "Same grades on paper means the same diamond"

Two stones with identical carat, color, clarity and cut grades can still look different. Inclusions sit in different places, proportions vary within the same cut grade, and some stones simply perform better.

What to do: use the report to narrow the options, then judge the specific stone: where the inclusions are, its proportions, and how it looks in real light.

Myth 4: "Lab-grown diamonds are fake" or "they should cost the same"

Both are wrong. Lab-grown diamonds are real diamonds with the same chemical and physical properties as natural ones. But they are priced very differently: they usually cost a fraction of a comparable natural diamond, and their resale value is much lower.

What to do: decide which you want before comparing quotes, and make sure every quote clearly says natural or lab-grown. A lab-grown stone priced close to a natural one is a red flag.

Myth 5: "A certificate is a certificate"

Grading labs are not interchangeable. For natural diamonds, GIA is the industry benchmark. IGI is the most common lab for lab-grown diamonds. Store or "in-house" certificates are written by the seller and don't let you compare the stone with the market.

What to do: compare stones graded by the same lab, and verify the report number yourself (GIA reports can be checked for free with GIA Report Check on gia.edu).

The common thread

Every one of these myths comes from turning a good starting point into a rule. Quotes should be judged stone by stone, with the report, the price and the fine print side by side.

If you have quotes and want an independent opinion, Ring Verdict gives you a clear answer in 24 hours from a GIA Graduate Gemologist with no jeweler commissions.

Felipe Araneda is a GIA Graduate Gemologist (Carlsbad, California) and the founder of Ring Decision. Verify the credential.