Rubies are one of the most naturally hard gems around and belong to the class of mineral known as corundum, which is second only in its hardness to that of moissanite and diamond. Therefore, you can be assured that any Ruby Rings, Ruby Earrings or other Ruby Jewellery, should be robust. If corundum is found in any other colour to that of red, it is then known as sapphire.
Make up of Ruby
The chemical formula of Ruby is Al2O3:Cr and it has a Mohs’ Scale Hardness of 9.0
What to look for
For those more sophisticated or simply more concerned of potential buyers, it is useful to know about the colour, clarity, carats, cut – better known as the four C’s.
Colours of Ruby
Depending upon the amount of the naturally found trace element known as chromium, gives the ruby its colour ranging from luxurious pink-crimson, to deep blood red.
The base colour of a ruby is known as the Hue, and they tend to follow through red to oranges and then to purples in various shades.
Colour purity and intensity is known as the Saturation. This is essentially how much the hue is masked by grey and brown shades.
The tone of a gemstone is simply the colour ranging from light to dark.
A ruby that has a medium/dark tone and bright hue are known as being “Pigeon Blood” red. These are mainly from the famous mines in Burma, are the most sought after, and therefore, control the highest prices. Generally accepted as being the best.
Clarity
All naturally occurring rubies should have imperfections, including internal colour impurities and outer surface blemishes.
More expensive rubies will display fewer “needle” or “silk” internal rutile inclusions, and just as with diamonds, the clearer the stone the more expensive it becomes. Only the most expensive of stones will show little inclusions, and this helps jewellers to more easily determine if a stone is real or not.
A six point asterism or “star” effect is shown by some rubies which are then shaped into cabochons to perfectly accentuate this “star” property.
The GIA system of grading clarity is the most widely accepted, and ranges from the best being VVS (very, very slightly included), VS (very slightly), S1-S2 (slightly) and I1, I2 and I3 (included in varying degrees).
Ruby Inclusions
Internally – Such as the silk rutile which is preferred, needles and cracks, as well as fingerprints, colour zoning, halos, chips and cavities.
On the surface – scratches, nicks and abrasions.
Transparency of Ruby
This is the degree of visibility that is seen through a ruby and is an often-overlooked characteristic. When discussing rubies transparency is stated as follows:
Transparent – This is a stone that has excellent brilliance and remarkably few inclusions allowing all objects that are viewed through it to be seen clearly.
Semitransparent – When looking through the stone objects may look slightly blurred or unclear to the eye.
Translucent – external objects are difficult to determine when viewing through the stone. Light will pass through them, but they are diffused.
Semi-Opaque or Semi-translucent – Because almost no light passes through the gemstone, objects cannot be seen clearly through the gem.
Opaque – No light passes through the ruby and objects can hardly be seen.
Ruby Carats (weight)
After colour and clarity, then the next critical factor in the value of a ruby is the size. Although it is usually more sought after to have bigger gems for obvious reasons, a smaller “pigeon blood” red example will usually be dearer than a larger paler red example.
Ruby Cut
These days cutters tend to prefer to shape rubies into ovals and cushion shapes, instead of round, even though rounds are more prevalent in diamonds. Rubies are somewhat more scarce and expensive, so, by using these shapes lesser of the original “rough” structure is lost during cutting. This therefore means that when they are shaped round then they will be more expensive because more “rough” is lost in the process.
The quality of cut in any Ruby Rings (just like all gemstones), can make the difference between an average gemstone, and an excellent gemstone. Esthetic value is always affected by the quality of a cut, because the better the cut, the more light reflection and sparkle the stone will send out.
With the superior quality ruby gemstones, a ratio of depth to width of approximately 65% to 80% is typically achieved. Quality gemstones should also always show an excellent symmetry, so when you look through the side of Ruby Jewellery you will see better light reflection and sparkle.
I thank you for reading my article on the make up of Rubies.
If you want the best Ruby Rings and other Ruby Jewellery, then John S Stewart has over 30 yrs experience in the jewellery trade, and he recommends visiting Globe Jewellery now!