If there is one subject in gemology where no-one agrees with anyone else, it’s this age-old question.
T he issue of “At what point does a Pink Sapphire become a Ruby?” can be pretty ambiguous and personal and can get some gem-traders into hot water running the risks of clients returning gems, and also disputes with gem laboratory staff when their so-called “Ruby” comes back with a report stating it is a not-so-valuable “Pink Sapphire”.
The stage for confusion is set from the fact that Ruby and Sapphires are chemically and structurally identical. Treated as a single group under the mineralogical term corundum, the gem trade splits this single group into two categories based on perceived colors alone:
Rubies — Red corundum only.
Sapphires — Blue corundums and all other colors. Sapphires without a prefix implies Blue Sapphire only.
Sapphires of all other colors come with a prefix e.g. Pink, Yellow and Green Sapphires. Prefixed Sapphires are generically grouped together under the term “Fancy Sapphires”.
While the above definitions seem straightforward, confusion arises when two parties can’t agree on the definition of the color in question.
Pink and red share exactly the same hue position on the color wheel. Technically they are exactly the same color. It is the saturation or strength of this red hue that differentiates red from pink. The problem for the gem trade arises due to the border region of where pink stops and red starts, being completely undefined. What one gem laboratory may call a Ruby, another may call Pink Sapphire.
Drawing the Line — At What Point Does Pink Become Red?
It would seem the only difference between Pink Sapphire and Ruby is your own personal subjective perception. The following is a statement regarding Ruby and Pink Sapphire color boundaries by the International Colored Gemstone Association (ICA).
“Pink is really just light red. The International Colored Gemstone Association has passed a resolution that the light shades of the red hue should be included in the category ruby since it was too difficult to legislate where red ended and pink began. In practice, pink shades are now known either as pink ruby or pink sapphire.”
From a historical perspective, prior to the twentieth century, the term Pink Sapphire did not even exist. All red hues of corundum (including pink) were called Rubies. Sri Lanka, historical producer of Rubies, found itself being in a most curious position after the definitions or “industry goal posts” were changed. Overnight Sri Lanka went from being a Ruby producer to a non-producer.