The word synthetic is unfair as these Blue Sapphires are exactly the same just not dug up; enviromentally friendly, more affordable, luxury-looking birthstone of September Pendants with Celtic basic knots, from the Celt culture, date back over 2,500 years before Christianity Silvershake Created Blue Sapphire 925 Sterling Silver Celtic Knot Pendant with 18 Inch Chain Necklace, is shipped with anti-tarnish protection in reinforced gift boxes & satin-style pouches; guarantee far-outlasting competitors Birthstone of September is Sapphire, it’s rare and expensive; with much more bling for your buck, our synthetic sapphire is 'The' affordable alternative Silvershake Created Blue Sapphire 925 Sterling Silver Celtic Knot Pendant with 18 Inch Chain Necklace