TIFFANY QUAICH TOASTING CUP

I know it only has one handle.
A 'quaich' normally has two and sometimes three or four handles. But you will see many a one handed example in English silver.
"Quaich (cuaich in Gaelic) meaning "cup", are a uniquely Scottish invention. Having no apparent connection to any other European drinking vessel they have maintained their distinctive shape as a wide and shallow cup for more than four hundred years. There are some scholars who believe the shape evolved from the use of scallop shells.
Those of small size were for individual use, larger ones were to be passed around on ceremonial occasions in the same way as a "loving cup" or a "mether cup". It has two (rarely three or four) flat horizontal handles (named "lugs" in Scotland) extending level from the rim of the bowl.
Early examples were made of wood, bone or horn (sometimes with silver mounts), while later examples were made entirely of silver.
The centre of the bowl was usually decorated with a silver coin or an engraved disc or 'print', with coat-of-arms, initials, motto or familiar phrase such as a toast.
The disc served the function of masking and sealing the centre of the bowl where the points of the staves met.
The width of ancient examples ranges from 9.5 to 25 cm while modern examples are made in many sizes."
http://www.silvercollection.it/dictionaryquaich.html

This one has the shape of a traditional silver of bone example. It is marked on the rim of the bowl Tiffany and Co. under the glass handle or 'lug'.
Instead of a coin there are engraved initials "M.W.L.".

I bought it at the Salvo's and was intrigued by the glass form. Then I found the Tiffany mark.

Does anyone know who made these modern pieces for Tiffany?