Sorry, No Flawless Rubies
Watch out for surface cracks (feathers) that work into the stone. They weaken the ruby. Look for internal flaws that block consistency of color and reduce clarity significantly.
There is no such thing as a flawless ruby. The trick is to find a stone with flaws (identifying features) that donÕt leave it vulnerable to breakage or adversely effect its color. Clarity is the term used to determine how free from flaws a ruby is. External flaws are called blemishes, and you will hear them referred to as scratches, pits, nicks and abrasions. Internal marks are inclusions, categorized as cracks (feathers) crystals, negative crystals, silk, fingerprints, halos, cavities, chips and color zoning.
Every ruby you look at will have a variety of these flaws present, and as long as they donÕt ruin the consistency of color, they are acceptable. Except for cracks. If you find a ÒfeatherÓ that starts at the surface and works deep into the stone, its durability is likely threatened and you should consider another choice.
Now, since these flaws can render a ruby either worthless, priceless and anything in between, The American Gemological Laboratories (AGL) and The Gemological Institute of America (GIA) have developed grading systems for determining clarity. The AGL looks at flaws with the naked eye and ranges from FI (free of inclusions) to EI1-3 (extremely included) with several levels in between.
The GIA works with 10x magnification and top quality is VVS (very, very slightly included) and bottom is Dcl(declasse) and again the range of variables is numerous.
Many jewelers employ their own scales (like A to AAAAA) so ask how close to the top of the AGL or GIA scale his definition of a particular stone lands.
Examine the ruby for clarity the same way you do for color; various backgrounds, light sources, from the top, bottom and sides, and under magnification.
Think of your ruby like you do your spouse and learn to love them the same way, warts and all.