How to Buy an Engagement Ring - Part 2: Why buy a diamond?

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How to Buy an Engagement Ring? - Part 2: Why buy a diamond?

Why buy a diamond

How to Buy an Engagement Ring - Part 1: Basics and Budget

How to Buy an Engagement Ring - Part 3: What is diamond cut?

How to Buy an Engagement Ring - Part 4: What is diamond clarity?

How to Buy an Engagement Ring - Part 5: What is diamond color?

How to Buy an Engagement Ring - Part 6: What is diamond carat?

Step 3: Why buy a diamond?

Ignoring the dubious history of the diamond industry, diamonds are actually cool minerals. This is coming from a professional gemologist and a gem stone dealer who doesn’t actually sell diamonds. Yes diamonds are  abundant and  expensive, but you’re not reading this because you have a choice in the matter. Humor me.

In comparison to other minerals, diamonds have a unique visual experience. I can say this because I look at gems all day. A good diamond is radiant, crisp, and sparkly. There are very few natural gems that compare. We can describe the visual qualities with three terms:


Copy and paste definition: It is the quality of the surface of a gem. As gemologists, we use luster to quantify the amount of light for gem identification. To see a tangible example, compare the surfaces of glass and any object with a sapphire crystal lens, such as a cellphone or expensive watch. When you position both surfaces to reflect light, you will notice that the intensity of the reflected light will be different. The sapphire crystal will reflect more light than glass. You can also compare glass and plastic. Luster is a function of the optical density and polish of a gem. The better the polish, the better the luster. In comparison to other natural gems, diamonds have a high optical density and the highest luster. Luster is especially noticeable in a high quality diamond. My own annecdote: I was at a professional basketball game, and I could see the white flashes off a coach’s diamond studs while sitting in the upper bowl. You can argue that the stadium lighting was flattering, but no other natural gem will behave like that.


 The technical term for fire is dispersion. Copy and paste definition: it is the splitting up of white light into its individual wavelengths (ROYGBIV). In simple terms: fire is the amount of rainbow colors you see inside a gem. The amount of visible dispersion is a function of the difference between the values of the red light and violet lights. These lights are emitted after refraction within a gem. Dispersion is not related to optical density, but rather the crystal structure. Diamonds also have a high dispersion in comparison to other natural gems. Also, many natural colored gems usually have a body color that masks the some of the rainbow colors from refraction. Moissanite is a notable gem material with higher dispersion, but I will discuss it later in its own section.


Copy and paste definition: It is the degree of brightness of all light that interacts with a gem. This includes light reflected off the surface and light refracted off the crown and pavilion facets. In simple terms: it is the amount of light reflected off the surface of the gem (luster) and refracted around its interior (scintillation - Copy and paste definition: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond). A brilliant gem will scintillate/reflect light back to you. If light passes through a gem without internally reflecting, it has a glass-like appearance and is not brilliant. A simple test to see brilliance is to hold a gem with the table facing you and move your finger behind a gem. If you can’t see your finger behind the gem, then it is internally reflecting light and bouncing back to your eye. The quality of the internal refractions is a result of the optical density and cutting patterns of the gem material. Diamonds are one of the most optically dense natural minerals, and as a result, they are more efficient to cut to produce brilliant gems. Scintillating gems with lower optical densities, such as tourmaline or peridot, tend to be bulkier and bulb shaped.  This results in a heavier, and more expensive gem [in comparison to less brilliant gems of the same type].

My Opinion on Why Buy a Diamond

Unlike other natural white gems, I think diamonds have an excellent balance between these three properties. So there you go, this is why I think diamonds are alright as a colored stone gem dealer.

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