Sterling Silver Thimble with no apparent makers mark

HI there,

My friend asked me to appraise one of the thimbles in his collection.

I have, however, come to a dead end so i am turning to you for assistance.

The thimble is made of sterling silver, with the appropriate stamp (excluding makers mark, fineness and province number), the shape seems to fit most (at leat in my eyes) the style of a USA made thimble. The main body is rather confusing as the dimples arent arranged in any particular way, and are more or less random.

There may be a poorly marked makers mark underneath the tarnish but we aren't wanting to risk devaluing the item by cleaning it.

Any help would be greatly appreciated.

Thanks in advance,

Jack Fowers