General
My beads and vessels are made individually in a flame, using rods of different coloured glass. They are slowly cooled and then, once carefully cleaned, assembled into jewellery using Sterling Silver and sometimes other small glass beads to finish it off.

Silver Cored Beads
All these beads are individually handmade by me, Madeline, in Devon, using rods of coloured glass. The Sterling Silver Core is individually cut and formed to fit each bead. The silver tube goes right through the bead, and therefore it cannot come out, it will also protect your chain from scratching or scuffing.  

They should fit most European Bracelet styles including Pandora, Troll, Biagi etc. I usually mention the internal size of the hole when describing a bead for sale so you can check

As far as I know the approximate measurements (at the point where they are thickest) for some of these bracelets are as follows

Troll : 3.4mm - 3.7mm (depends how much end ring is flattened into an oval)
Pandora: 4.2 - 4.7mm
LoveLinks: 4.7mm (I will update these as I find out more!)

All my beads have been slowly cooled in a kiln after they are made to make sure that there is no stress in the bead so that it is unlikely to crack or break under normal circumstances.(that is to say wear it and it will be fine, put it in a jewellery box it will be fine, throw it on concrete and it might not!)

Vessels  
my vessels are made form the same type of glass as pyrex, meaning that although they are thin, they are quite strong really, that said , as this item is made of glass, it can break if treated roughly. I recommend keeping it separate from other jewellery when not being worn, keeping it in its own box would be advisable.
Do not expose it to extremes of temperature. To open or close stoppered vessels, a gentle twist should do it, but hold the vessel by the neck, NEVER by the handle.
Ground glass can be effective in sealing liquids inside the vessel, but I would recommend testing individual vessels with water before trying any other liquids such as perfume or aromatic oils, as I do not gauarantee that they are liquid or airtight. Or you could put a small keepsake inside instead.  

Silver
To clean the silver, use a silver cloth or a foaming silver polish,using a small brush may help you get into any intricate parts. A silver dip may strip the silver of its protective layer and leave it vulnerable to tarnishing again quickly. some glass surface finishes may not survive this process. Always rinse the piece with lots of clean water after using foam or dip and dry it thoroughly.