Birthstones / July
July: Ruby, Lab-created ruby
Traditional: Ruby · Red to purplish red · Mohs 9
What it is
Red corundum, the same mineral as sapphire, colored by chromium; from Myanmar, Mozambique, Thailand and Madagascar. Heat treatment is routine and must be disclosed; lead-glass-filled rubies are a composite and far cheaper. Lab-created ruby is the same chemistry grown in a lab and has been made since 1902.
In the glossary: Ruby, Lab-created ruby.
Care
Soap and water; ultrasonic is fine for untreated and heated stones, never for glass-filled ones.
Before you buy
Natural untreated ruby in a clean red is among the costliest gems per carat; a large bright 'ruby' at a modest price is lab-created, glass-filled or garnet. Read the word before the name.
Sources: Jewelers of America modern birthstone list; GIA gem encyclopedia; FTC Jewelry Guides on treatment and lab-growth disclosure. Clasp & Lens does not appraise or grade stones; what a listing says is the supplier's statement.