[This posting was prepared at the same time as Frank made his comments above - I have left my comments as they were for completeness. But please note that my summary may differ in some respects to what Frank now shows in his Scotlands Glass site(s).]
The first range of "stones" used for the CG jewellery were made by Paul Ysart, and they were in use from 1969/70 to approximately 1973 (there was a period when the stock of "stones" continued to be used after Paul had left CG in 1970/71). After Paul left, Peter Holmes took over with making of the "stones" and from 1973 most would have been Peter's work.
Although lots of different individual cane designs were used to make the stones, the finished items from Pauls work did have a "sameness" about them. This was also true of Peter's work except that his canes had what I would call a more "fluid" look about them. Even so, it is often difficult to decide whether a "stone" was by Paul or Peter.
After Peter left CG (around 1977), again his remaining "stone" stock was used and then other workers made the canes and these tended to become less complex and the colours were perhaps less varied.
The pendant shown has marks for Edinburgh 1981 suggesting the canes and the "stone" could have been later CG work. However, I think it may be one from Peter Holmes' stock used in later years.