I have not heard of Tartan Crystal [rather than "Tartan Glass Studio"], but there is a company called Crystal Engraving, operating out of Wales, whose business is engraved items, presumably using blanks from elsewhere. Amongst their current lines is ...
... A pair of cut Tartan Crystal champagne flutes with a panel for engraving
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Crystal Engraving also provide blue presentation boxes with blue silk lining, like the box shown in that eBay listing. Perhaps the engraving company also add names to the boxes according to the maker of the item that is engraved?
Maybe an email to the engraving company could help?