The cut that we choose does have some affect on the brilliance and the ultimate overall look of the gem.


Deep cuts are another thing to consider. I find no issue with deep cuts. Matter of fact, our bestselling cut, which is the Portuguese round, which is citrine, is a Portuguese round gem. Its depth is probably 85% of its width, so it's 85% depth, meaning if it were 10 mm wide, it would be 8.5 mm deep. This is one of our most popular cuts because it's one of the brilliant cuts that we do.


It's a little more of an issue with setting, so setters have a little more problem with it. Standard heads are probably not deep enough to carry the extra depth needed, but the brilliance is extraordinary.


I have, always go back to when I was traveling to Bangkok and looking at parcels of sapphires, and there may 500 stones in a parcel. You're looking at them, and one just looks at you and just goes bam. It just, amazingly brilliant, and then you take it out of the paper, and it looks like a snow cone.


It is 150% depth. Extremely deep, impossible to set, so you can't buy it, but extra depth does not affect brilliance. It often improves brilliance, but the issues of setting and the issues of your paying for weight, and there's a lot of weight in the belly, so you get a stone that looks like a five carat, and it really weighs seven or eight carats, and you're paying per carat, so those are couple of the issues, but brilliance is definitely not the issue of an overly deep stone.


Another benefit of deep cutting is how it affects color. The deeper you cut a stone, the darker the stone will be. It's just like looking through water. If you look, the deeper you look in the water, the bluer it becomes, so this is one more benefit of a deep cut.


Finally, in cut, you want to look at the symmetry of the stone, just how symmetrical it is when you look from the crown. Probably the more common issue is how symmetrical it is when you look at the pavilion of the gem because often you'll look at gems and they look symmetrical when you look down on it, but if you look from the back, the culet of the stone, the bottom part, very often is off-centered. That's going to produce a much less brilliance stone. It's going to produce something that looks distorted when you look at it from the surface.


Look closely at how symmetrical it is from all directions. When I cut a stone, I use a machine that doesn't allow me to cut out of symmetry. I mean, I could force it, but you really want a highly symmetrical stone. The facet should be facing across from each other. When you use a high quality machine, that's exactly what you get. This facet reflects to this facet. If this facet's turned somewhat, it will not reflect correctly, so symmetry is also very important in the cut of the gem.


Our four C is carat weight. Named after the carob seed, it was used in ancient times because the carob seed had pretty much the same weight. You could pick any carob seed, and it would be a similar weight, so it was used in weighing items including gems in the past.


Carat is a fifth of gram. Carat has a pretty dramatic effect on how gems are priced. If we took a five carat ruby, it could be 40,000 a carat, whereas an emerald, which we consider to be as valuable as ruby, is only 9,000 a carat in the same size, and this is based on the rarity by size.


Tsavorite garnet compared to rhodolite garnet, the tsavorite is 8,000 a carat, and the rhodolite garnet is only 200 a carat. Tanzanite, little different situation. Tanzanite prices aren't so dramatically different by weight. If you take a two-carat tanzanite at, say, 500 a carat, you can also buy a ten carat, much bigger stone, for only 700 a carat, so just a slight difference, as compared to sapphire where a two carat can be 15,000 a carat, and the ten carat can be 5,000 per carat. The weight of a particular gem or the difference between different species of gems can be pretty dramatic with differences in weights.


The apparent sizes of gems based on their weight can be affected by cut. We talked about the Portuguese round gem, this citrine that weighs 29 carats. If you cut it to a standard ground, it'd only weigh 22 carats. They would both sell for the same price per carat, so the apparent size you get from a standard round compared to this Portuguese cut is going to be much bigger for a much less price.


The other factor that is involved is specific gravity. Specific gravity is the density of the gem, like the difference between lead and glass or whatever. Much difference in specific gravity. That affects the apparent size of a gem. The difference between sapphire and emerald is fairly significant. If you put a one carat sapphire next to a one carat emerald, the emerald will look much larger, even though it weighs the same.


Another thing that affects the price of gems and the price by carat size is their availability. Often, we'll run into times where they find a pocket of gems, and all of a sudden, there's a lot of gems available. This has happened recently in Rwanda, amethyst, many of the garnets, the malaia garnet I showed you earlier. Because it was available at the time, you could buy a larger gem much cheaper than you normally could buy it. The availability on the market and the demand in the market can affect how gems are priced per carat.


Hopefully this will help you in the process of buying colored gem stones and ultimately lead you to one of our websites where we sell colored gems including,, and


I'm Steve Moriarty from Moriarty's Gem art. See just some of our gemstones online here.