An authentic red ruby would look bright red when seen under light. A pale colored ruby might not be completely authentic. Depending on the number and quantity of trace minerals found in a ruby stone, each sample would have different clarity. The interesting thing about chromium is that it inhibits the growth of the crystal after a certain level, so you would most commonly find rubies only up to 10 carats. But stones below 5 carats are also not that valuable.
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