If it is possible to put together two tempered glass parts, how you would do it?

If it is possible to put together two tempered glass parts (for example a tempered glass ball of 10″ diameter, which had to be made it in two parts due to its design), how would you do it to make that union mark almost invisible?
WIth a special glue?, with a special sealant?, heating that area?
If it is not possible, why not?, how can I put together those two parts, that there is no way to get it just in one part.