Inclusions

Gas bubbles, feathers, crystals, veils, carbon spots, lily pads, silk, jardin, etc. There are maybe more types of inclusions than there are gemstone varieties!

I seem to have spent the last week talking about inclusions with various people. I figured that since I’ve been talking about it so much, I might as well turn all of that discussion into a blog entry. This post is pretty generalized. It is more of a take on my view of inclusions, how they affect the beauty/appearance, and a little bit about their effect on value.

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Inclusions don’t bother me in colored stones, but they do (most of the time) in diamonds. But that’s because I’m all about color. When I design, typically diamonds are accents, unless, of course, they are colored diamonds.

If the color is right, and the price is right, inclusions are great. They show the stone is natural and they usually lower the price. Some inclusions are prized, like silk in rubies and sapphires, horsetails in demantoids, jardin in emeralds, and they make the stones more valuable.

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Now, why would they make the stone more valuable? Well, they can show provenance, they show evidence of treatment and can make for some stunning effects on the gem. Without silk, there would be no gorgeous velvet vivid blue sapphires and no huge markup for a Kashmir blue sapphire.

All of these gems are more rare than diamonds, so inclusions in colored gems are acceptable, so long as they don’t interfere too much with the overall appearance of the gem. Diamonds really aren’t that rare, despite what the diamond industry might want you to believe, so insisting on a stone being at least eyeclean doesn’t really narrow the diamond field that much. But if you’re looking for an internally flawless sapphire, ruby or spinel for instance, you might be waiting for quite a while.

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So, clarity between diamonds and most colored gemstones just a completely different ballgame. It is inclusions and differences in chemical composition that can give gems their coloration. There wouldn’t be the electric neon glow of Paraiba tourmaline without copper.

In my opinion, the inclusions don’t necessarily detract from the beauty of the stone, and I think they are super cool to look at under magnification, not to mention, as I said before, they can create awesome visual effects within the stone. For instance, I love the gas bubbles seen in this Mahenge – they remind me of carbonation bubbles in soft drinks.

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Lets get a little bit more specific, with spessartite. Typically I actually prefer sugar inclusions in Loliondo, because they give it a glow that they don’t have otherwise, but I like clean stones too – though they tend to look brown in certain lighting because there aren’t any inclusions to break up the light reaching the facets. So then the facets reflect everything and typically it looks brown because of the orange color. Spess is very complicated.

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If colored gemstones weren’t rare, and there was a plethora of these gems out there, the way they are with diamonds, then yeah, I’d insist on eyeclean, the same way I do for diamonds. But they aren’t. All of these beautiful little colored stones are actually pretty rare, even more so in the stone’s ideal colors, which explains the mark up!

So. I give a big thumbs up to inclusions. Inclusions and I are friends.

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Gemstone Vocabulary and Anatomy

I decided to put together a glossary of sorts of gemstone terms, or terms that I use relatively often and might not be familiar to those who aren’t well versed in gemstone and jewelry terminology. Something I wish I had when I was first learning!

This is an endlessly growing and changing document, and will need continuous updates to keep it useful. Please let me know if any suggestions for terms, or comments you might have!

Adularescence – milky glow that moves as the stone moves, originates from within a gemstone and is caused by inclusions, occurs in the presence of stronger light conditions.

bezel set – a way of setting a stone with solid metal completely surrounding the stone, pushed down over the stone’s girdle

brilliance – amount of light reflected back out of a gemstone, a direct result of a stone’s refractive index

brilliant cut – a facet design radiating from the culet of the stone, on a perpendicular plane from the girdle of the stone

cleavage – tendency for a mineral to break along distinct planes dependant on how the mineral grows

colorless – a stone that is not known for being without color, having zero saturation. Examples: sapphires, spinels, garnet, tourmaline, topaz

crown – the facets from the girdle up to the table, the height from the girdle to the table

culet – the pointed tip of a stone formed by pavilion facets. Antique diamonds may have “small” “medium” or “large”. Modern cut diamonds typically do not have a culet, the pavilion facets meet at a point.

dispersion – the ability for a gem to divide the light into spectral colors

facets – a flat plane cut onto a gemstone

fat belly – when a pavilion is cut to preserve weight, instead of forming a cone, it is more bulbous and round on the bottom

fire – see dispersion

fluorescence – reaction of trace minerals causing the stone to glow a specific color when exposed to UV light, typically blue, yellow and red

girdle – the circumference around the stone where the crown and the pavilion facets meet, it can range from very thin to very thick, and can be faceted or rough.

keel – an edge formed by pavilion facets. typically found in elongated cut stones

kozibe effect – culet reflected around the stone

luster – light reflected from a gem’s surface

meet – the edge in which is made when two facets line up in faceting

monochrome – varying tones of one color, white-gray-black

MRB – modern round brilliant

OEC – Old European Cut

OMC – Old Mine/Miner’s Cut

pavilion – the bottom part of the stone, typically cone shaped

pleochromism – the characteristic of having different colors visible from different angles

RI – refractive index

Rose cut – stone cut into a dome type shape with a flat bottom/no pavilion, and the crown is a hexagon shape with triangular facets, meeting in a low angled point on top, typically cut in a round shape, but may also be cushion, pear, oval or marquise.

saturation – how pure and intense a color appears. Low saturated tends to be gray, highly saturated is vividly colored.

silk – the appearance of a stone looking slightly cloudy, which bounces the  typically caused by inclusions referred to as silk,

spread – the size of a stone when looking top down, measured by the diameter of the girdle. Typically used to compare one stone to another.

step cut – a facet design on a parallel plane from the girdle of the stone, typically angular in shape. Emerald, baguette, carre, asscher are common types.

tilt window – when a stone is viewed at an angle that is not straight down into the stone, and you can see through the pavilion

table – the flat top facet of the stone

window – when a stone is cut at the wrong angles for it’s type, the see through portion in the middle is called a window

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Window illustration