Skip to content Skip to navigation

Harriet Kelsall Jewellery Design
Blog

Responsible Jewellery Council Certified
Harriet Kelsall's Facebook page Follow Harriet Kelsall on Twitter National Association of Goldsmiths Logo British Jewellers' Association Logo
Angela Godden
17th June 2008 16:35

Gemstone mystery

 

I found this very interesting....and it was fun working through.....

One of our customers bought in a ring with a 10-12mm round red/purple stone in it. The colour was quite rich and strong. She wasn't sure what it was, possibly a sapphire? synthetic? we decided to get to the bottom of it for our customer and our own curiosity! We originally thought to send it to one of our stone dealers for a closer inspection, however as i'm studying the foundation in Gemmology at GEM-A London ( www..gem-a.com ) we felt it would make better sense to take it with me to one of my classes and ask my tutor and fellow students for their opinions whilst having a good look and test the stone using the tricks of the trade :)

To identify a gemstone its always nicer to be able to feel the stone and look at it from all angles, however its difficult to do this when the stone is set into a piece of jewellery. You can still use the lustre of the stone, colour and identifiable features when having a closer look with a loupe, especially if the setting around the stone allows you to.

It was a real process of elimintion, this is how we worked through it:

At a glance synthectic sapphire? but strange colour, maybe coloured glass?

When tested on a refractometer we got a reading for quartz. A refractometer measures the ray of light - when a ray of light meets the surface of a polished gemstone, somelight is reflected, but most passes thought it. Because a gem has differnt different optical densiy from air, the light slows down and is bent from its original path (refracted) The amount of refraction within a gem is called a refractive index (RI) and this can be used to identify a stone.

Looking closer at the stone there was a slight variation in colour on the top half to the bottom half and a circle of black dots in the middle - the matkings too precise to be natural inclusions - could this mean its a doublet and two peices of material joined together......

When placing the stone into a cup of water it showed a colourless mineral at the top and the bottom of the stone which we believe to be Rock Crystal with red adhesive holding it together through the middle which gave the effect of a red/purple stone all over.

This stone appeared to be a Soude triplet.

Soude - soldered

Triplet - 3 layers

We got there in the end!

Angela :)

Angela Godden
 

Archives

Entries by date

RSS Feed

Click here for our Blog RSS Feed

What is RSS?

Weddings Blogs - Blog Catalog Blog Directory

British Blog Directory

Blogarama

Directory of Design Blogs

The Blog Directory

 
 
  • Harriet Kelsall Jewellery Design, North Barn, Fairclough Hall Farm, Halls Green, Weston, Hertfordshire, SG4 7DP, England
    Phone: +44 (0)1462 790565 Fax: +44 (0)1462 790140 enquiries@hkjewellery.co.uk
  • Harriet Kelsall Jewellery Design, 6/7 Green Street, Cambridge, Cambridgeshire, CB2 3JU, England.
    Phone: +44 (0)1223 461333 Fax: +44 (0)1223 365269 cambridge@hkjewellery.co.uk

Our designs are legally protected by design right and copyright law and cannot be copied.