African blue chalcedony can be quite blue by nature, so even when it is quite bright, it may be natural.

Here is an image of a piece of African blue chalcedony in the rough, this is a very nice piece and is naturally this color. I have made beads from this material and they come out quite nice. If it weren't for a hurting back from an accident a few days ago I would scrounge a bead, I know Joyce has one so perhaps if she has time she will post an image.

Natural chalcedony comes in many colors it is just not that common, I have some true purple out in the studio that is amazing,if I get over there later today I will take an image of it and post it.

All my best .......... Danny

You asked if the beads will come out as blue as in the rough in the image you posted. More than likely the beads will not be as saturated as it looks in the rough. Usually the outer rind makes the color look a bit darker than when it is removed. The material you posted would with out a doubt make some very nice beads.

After my first post I thought about it and it dawned on me that there are many colors in chalcedony that we do not think of as being chalcedony. One that came to mind is Chrysoprase most don't think of Chrysoprase as chalcedony but it is, some of the finest green beads I have ever made were from Chrysoprase, many would think they were best quality Jade.

I have attached another image of chalcedony with color. One is purple and the other is a pink limb cast. Thomas "tasart" was kind enough to gift me the blue and also the purple I have posted and I must say they are some of the finest in these colors I have seen.

All my best ........ Danny

My colouring question:is there a way to see the difference between natural and coloured/dyed chalcedony?
Thank you!

If you have seen plenty of jadeite or nephrite it is very easy to distinguish the difference, these two stones have certain characteristics that are unique to them. Chrysoprase again is as near agate as it can be so Chrysoprase looks much more like agate than either jade material.

When forming in solution as the silica drops out of the solution the first thing to form is a common clear opal, next calcedony forms and then agate and finally Quartz.

My colouring question:is there a way to see the difference between natural and coloured/dyed chalcedony?

Many stones that have been dyed have telltale areas under magnification jade is prime for this. If you look under a microscope into the stone there is almost always an area or two where the dye has puddled.

I looked at the website you got the blue Calcedony image from. It seems funny they have those four or five super high grade pieces of rough in the image and then if you look at the cabs they are offering the cabs are nearly clear with little to no blue. I think once in awhile they find the best blue but as with all stone the best is usually less than 1% of production.

I figure the beads you saw were made out of this 1% back in the day and that is part of the reason they are now so expensive.

All my best ....... Danny

You can buy nail polish remover saturated on soft cotton pads, and I check for dye by rubbing a corner of the suspect stone with an acetone saturated pad and checking the pad for colour.

Best ask permission first.

People sometimes ask me "How can you tell the difference between old and new?" I recommend buying the beads you know are new so that you can train your eye to identify the new ones. Then you will have a head start trying to find clues of antiquity in the ones which do not fit the mold.

Frederick

The beads I saw in Paris were ancient beads, I have no doubts about that. They just had all this quite intense colour. It is a pity I could not take a picture.
So should I assume noone would colour less attractive -colourwise- ancient beads. Has anyone heard of this practice ?

If antique and ancient beads are being more recently treated to change color, it is probably a trade secret. You are the first to mention this possibility to me.

Frederick