Hatpin holder?

[ssf2]

This was marked as a hatpin holder, but there are no holes in the top like most I have seen. Perhaps it is a small vase? I love the shape of it and thought the pattern was interesting, so I bought it.

[mart]

Could be either one !!  Not all hatpin holders had the top with holes !! Ladies back then were known to appropriate a small vase for  a different use !!  Nice one !!

[KC]

There were many hatpin holders that didn't have the "salt/pepper shaker holes" that one comes to expect for hatpins. Like Mart said there were many things that were dual purposed.

What is the height of the piece and width of opening? 

There were many that weren't porcelain/glass - Such as these at liveauctioneers
https://new.liveauctioneers.com/item/46814770_two-silver-hallmarked-hatpin-stands-the-first-modelled

and many that didn't look like typical stands (ebay, goantiques and other sources)

[ssf2]

It is 4 inches tall. The top of the opening is 1 1/2 inches wide, but narrows to 1 inch due to the shape of the piece at the top.