Hi Jim,
The Coldstream Guards never went to India, but they fought in the Crimean War in 1854-56 and a lot of the officers purchased new swords (and revolvers) around that time as a result. However, some officers in the Coldstream Guards did have connections to India, having served there with other regiments previously or having family connections there.
In terms of the dating, all Wilkinson officer's swords from 1854 are numbered, as is this one, and the number dates it to 1855. In many cases the record books are able to identify the purchaser of the sword, going all the way back to 1854 when the records and numbers started, but in this case the particular book that this number was contained in has been destroyed by flooding! Wilkinson were making swords from 1844 onwards and at least from 1845 were using the interlinked triangles (not a Star of David
). As Wilkinson had a formidable reputation and Crown support, other makers started copying the motif from the 1850's onwards.
Going back to this specific sword - because the original record ledger was destroyed I only have two leads to identifying the onwer - firstly these Sanskrit characters shown above and secondly the engraving on the other side of the blade which shows a ducal/viscount coronet over interlinked letters (which appear to be the letter D mirrored).
I can view all the officers of the Coldtream Guards from Hart's Army Lists, which are viewable on archive.org
Thanks for the help,
Matt