real amethyst or heat treated ?

[rockette]

Was told that crystals can be heat treated in order to appear like amethyst. If so, how can you tell the difference? Some of these appear to have
been tumbled/polished. The stone in the middle looks at if it is in original state. Again, no idea where they were collected.

 

[Cariboo5]

Very nice, and you are correct as Amethyst is often heat treated to deepen the color.

If I had to guess just judging by the lightness from your picture these look more of a natural color to me.....

 

[Eu_citzen]

Amethyst if heated turns to citrine. (i've done this myself a few times)

 

[JohnnyFlake]

The light color of the stones, leads me to believe that they are not heat treated. When heat treated the color is intensified dramatically.

 

[Eu_citzen]

I wonder where everyone got the idea that you get a deeper colour from heating amethyst?
Go about half-ways down this page:
Heat Treatment for Gemstones

 

[mirkaba]

My girlfriend has a thing for citrine. I have heated several amethysts to make citrine for her. The darker the amethyst the darker yellow the citrine after heating.