With the use of some very simple techniques, it is possible for jeweller to identify some gemstones and some gemstone and diamond treatments with the use of some very basic jewellers tool. 

Diamonds

            Laser Drills:  Diamonds which have dark or black included crystal can be laser drilled in order to improve its overall appearance.  In some cases, the apparent clarity grade may improve.  With the use of a laser, it is possible burn away a dark or black included crysal leaving behind a white coloured residue.  In most cases, this treatment is easy to identify by the long tubels the laser drill leaves within the stone.  See figure 1.  to further identify that the tuble that is seen is a laser drill, it is possible to follow the laser drill to the surface and the laser drill hole can be seen on the surface of the diamond.  See figure 2.

            Laser drill hole treatments are fairly easy to identify ad should be disclosed at during the transaction of the diamond. 
            The laser drill is a very stable treatment.
           
            Fracture Filling: The appearance of diamonds which have surface reaching fractures (feathers) can be improved by sealing the fractures with the use of a foreign substance.  in some cases, the apparent clarity grade can improve.  The foreign substance used is transparent with a similar refractive index as a diamond and is introduced into the fracture under pressure.   Fracture filling is sometimes identified as Yeuda treatment.
            The treatment is easy to identifiy by its distinctive violet/blue flash, which can be seen within any surface reaching fractures. 
            The stability of the treatment can range from very unstable to stable under normal daily wear and tear.  As well, some treaters provide a lifetime guarantee on the treatment.  Full and complete disclosure should accompany all transaction, as well, a full understanding of the stability of the treatment,

            Identifying Mossinite from Diamonds:
            Mossinites made their first enter into the jewellery industry as a vialble substitute to diamond in the mid 90’s.  they can be found in a wide range of sizes and shapes and are found primarily in the brown and yellow to very light brown and yellow range and of very high clarity.  The reason mossinites are considered a very good subsitue to diamond is the similar way mossinites and diamonds disperse light.  The most obvious method of identifying is by using a mossinite tester but the other way to identify mossinites from diamonds is to look for characteristic differences between the two stones.  One of these differences is how light rays behave within each stone: when a light ray enters a mossinite it is split into two light rays and exits the stone as two rays: whereas when a light ray light ray remains unchanged when it enters and exits a diamond.  This difference can be observed when the stones are examined with a 10X loupe.  When looking for the culet through the bezel and star facets, the culet will be doubled for mossinites and remain only as one for diamonds.