One way to make a birthday gift really special is to choose a piece of silver jewellery featuring her - or his - Birthstone. 
Most gem scholars agree that the tradition of birthstones arose from the Breastplate of Aaron: a ceremonial religious garment set with twelve gemstones that represented the twelve tribes of Israel and also corresponded with the twelve signs of the zodiac and the twelve months of the year.
We have been wearing our birthstone ever since.
Many different lists exist but below is the one most widely known and used.

What's My Birthstone

January is Garnet

Although garnets can be a wide variety of colours, it's the rhodolite garnet used in almost all garnet jewellery.
Rhodolite garnets are a deep glowing red, sometimes slightly pink in shade, sometimes very dark.
garnet birthstone jewellery
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February is Amethyst

Amethyst is one of the most popular semi-precious gemstones and is widely available.
Amethyst varies in colour from a mauve pink to deep royal purple.
Green amethyst is a gentle sage green colour and currently popular and available. 
amethyst birthstone jewellery
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March is Aquamarine

Aquamarine is at the top of the pecking order in the world of semi-precious gemstones.
A form of Beryl (in common with Emerald), it is available in various shades of aqua spanning the range from greenish aqua to blue aqua.
aquamarine birthstone jewellery
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April is Diamond or Rock Crystal

Allegedly, diamonds are a girls best friend but if diamonds are beyond your budget, rock crystal or crystal jewellery will provide the sparkle for less.
april birthstone jewellery
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May is Emerald

Emerald is classed as a precious stone and top quality, eye clean emeralds are expensive. These are reserved for prestigious jewellery.
may birthstone jewellery
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June is Moonstone

Moonstone, considered sacred in India, gets its name from its resemblance to the moon.
Rainbow moonstone is the most popular type of moonstone and is loved for its schiller (the blue floating light) and rainbow shafts.
june birthstone jewellery
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July is Ruby, Carnelian or Onyx

Ruby, a form of corundum, is a precious stone and like emerald, is expensive to buy the best quality gems.
Carnelian and onyx are semi-precious stones and much more various and affordable.
july birthstone jewellery
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August is Peridot

The bright lime green of peridots is lively and refreshing. Peridots are at their best when faceted allowing the light to penetrate that wonderful colour.
august birthstone jewellery
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September is Lapis Lazuli

Lapis lazuli is opaque. Its colour varies but the best lapis lazuli is a rich royal or navy blue. It has characteristic gold pyrite sprinkled through the dense texture and sometimes calcite deposits. These appear as whitish flecks.
september birthstone jewellery
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October is Tourmaline

Tourmaline occurs in every colour so if your birthday is in October, you have a vast choice.
Except for the very best quality stones, tourmaline is included. This is especially so in the larger stones.
september birthstone jewellery
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November is Topaz or Citrine

Blue topaz is available in 3 shades - sky blue, swiss blue and london blue. Swiss blue is the most popular and makes into fabulous jewellery.
november birthstone jewellery
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Citrine can be a pale straw colour but the most prized colour is the cognac or brandy colour. Citrines are readily available in large sized stones which make the most of this rich deep gold colour.
shop november birthstone jewellery
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December is Turquoise

Turquoise is a very special semi-precious gemstone with a long history of being used as a body adornment. It is mined in many places around the world, each site having its own characteristics.
Every piece of veined turquoise is unique.
december birthstone jewellery
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