Clarity: Professional purchasers in the gem trade prize clarity. While inclusions may not be visible to the unaided eye they change the dispersion of light and impact the stone’s “flash“, “fire” and appearance.

SI-1 This is slightly included stones. They are common. An estimated 90% of professionally cut rubies fall into this class. The inclusions can and usually do result in a somewhat lifeless stone with low luster, fire or “flash”. In other cases, the gem may give a dirty or soiled appearance. Mid size gems of 2 carats are common, Large gems above 2 carats and above are less common, but are typically not thought of as investment grade stones. An ideal application for these stones is where the finished product is intended to bring $80 to $150 per carat.

SI - VS This is slightly included and very slightly included gems, they comprise an estimated 8% of professionally cut rubies. The inclusions are less noticeable and in some cases the gem has good appearance if the color compensates for the impaired clarity. An ideal application can be for mid range jewelry. Retail per carat tends to be in the $100 to $300 per carat range (the range widens as the quality of the stone can be offset by the quality of the setting)

VS - These stones represent all but a minute portion of the remaining 2% of stones. VS ruby gems tend to have more of the “fire” and glow or luster that has historically made rubies desirable for fine jewelry. Retail per carat can range between $300 to $1,500 (the range widens again as accent stones, settings and style become more predominant determinants of value.)

VVS-IF is very rare and very prized in rubies - synthetics tend to be VVS-IF but can be detected by a gemologist. It is recommended that you purchase stones of this quality from trusted sources.

Cut: Gemcutters are not born, they learn their trade the way everyone does, by practice. Uneven facets and uneven overall shape tend to be the hallmarks of untrained or inexperienced cutters. Poorly cut stones tend to be shunned by retailers looking for anything other than lowest end merchandise. As with most businesses, gem cutting operations rarely give promising “rough stones” to novice cutters. The risk of ruining a valuable gem is simply too great. The best cutters get the best rough to work with. As gems move into the VS-SI and even more so, the VS category poor quality cutting tends to become less of a problem. When making a purchase look carefully at the reflections coming from the facets, check for uneven lines. If you can notice it in a picture it will be apparent in the stone when received. Stones with a dull appearance or stones that don’t show faceting in photographs are likely to have a poor cut.

Color: Color is a subjective evaluation. A pink ruby gemstone can give a wonderful appearance as does a “Pidgeon Blood”. Historically the color that has the highest value is Pidgeon Blood. Saturation is also a factor, the higher the saturation is, the deeper the color. A very low saturation stone is easier to look through, a high saturation stone gives a darker color.

Size: Carat weight helps determine a gem’s value as the available “rough” decreases geometrically as one looks for larger and larger gems. De-class stones, stones that lack transparency can be as large as a fist and still have uncertain investment value. Stones above 4 carats in a VS-SI or VS category are scarce.