Editing Ruby (section)

==Factors affecting value==
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Rubies, as with other gemstones, are graded using criteria known as the four Cs, namely color, cut, clarity and carat weight. Rubies are also evaluated on the basis of their geographic origin.

=== Color ===
[[File:Rubin (Corundum) - Hunza Valley, div. Gilgit, Northern Areas, Pakistan.jpg|thumb|Ruby (Corundum) - Hunza Valley, div. Gilgit, Northern Areas, Pakistan.]]
In the evaluation of colored gemstones, color is the most important factor. Color divides into three components: ''hue'', ''saturation'' and ''tone''. Hue refers to color as we normally use the term. Transparent gemstones occur in the ''pure spectral hues'' of red, orange, yellow, green, blue, violet.<ref name="wise">{{cite book|author=Wise, Richard W. |title=Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones |pages=18–22 |isbn=0-9728223-8-0 |year=2006|publisher=Brunswick House Press}}</ref> In nature, there are rarely pure hues, so when speaking of the hue of a gemstone, we speak of primary and secondary and sometimes tertiary hues. Ruby is defined to be red. All other hues of the gem species corundum are called sapphire. Ruby may exhibit a range of secondary hues, including orange, purple, violet, and pink.

<gallery mode="packed" heights="160">
Image:Ruby cristal.jpg|A naturally occurring ruby crystal
Image:Ruby gem.JPG|Natural ruby with inclusions
Image:Cut Ruby.jpg|A cut pink ruby
Image:Rubis, calcite 14.jpg|Purple rubies
</gallery>

=== Clarity ===
Because rubies host many inclusions, their clarity is evaluated by the inclusions’ size, number, location, and visibility. Rubies with the highest clarity grades are known as “eye-clean,” because their inclusions are the least visible to the naked human eye.<ref>{{Cite web|title=Ruby and Sapphire Grading Tools|url=https://www.gemsociety.org/article/ruby-sapphire-grading-tools/|access-date=4 May 2021|website=International Gem Society|language=en|archive-date=4 May 2021|archive-url=https://web.archive.org/web/20210504012848/https://www.gemsociety.org/article/ruby-sapphire-grading-tools/|url-status=live}}</ref> Rubies may also have thin, intersecting inclusions called silk. Silk can scatter light, brightening the gem's appearance, and the presence of silk can also show whether a ruby has been previously heat treated, since intense heat will degrade a ruby's silk.