Help please identifying silver pin

[BrazilianBombshell]

I appreciate any comments to help me identify this pin.  I know my paternal grandmother qualified as a midwife at the Marylebone Hospital in 1912, though it may not be connected to this pin.  Your suggestions are very much welcomed. 

[Ray T]

Simply looks like a Celtic Brooch to me. The hallmark might tell you more; although it doesn’t look like a real hallmark.

[Istrice]

A cast metal, Celtic patterned Penannular Brooch possibly in silver.
The markings on the underside of the brooch shown in the photo are too pixellated to make out any real detail.  With a better defined photograph of these markings (letters and symbols) in this area it should be able to tell if the material is cast silver, and if so who manufactured the item, and when and where it was assayed.
The brooch is well worn and may well have been a treasured possession.

Istrice.

[hepburn]

The two symbols at the bottom are interesting..They don't look like the rest of the pattern..I'd give the hallmark a clean with soap and a toothbrush to see them clearer.

[Sinann]

A Tara Brooch used for holding a cloak, often found as part of an Irish dancing uniform.

Based on The Tara Brooch
https://www.museum.ie/en-ie/collections-research/collection/the-treasury/artefact/the-tara-brooch/4e7de8cc-9cf5-4352-a20a-34caf1bf4d95

[hepburn]

Or the Penannular brooches..

[BrazilianBombshell]

Thank you all for your comments and leads.  I will clean it up with silver dip and post a better photo.  Thank you lots.

[Viktoria]

I agree with Istrice, I have one exactly the same ,in silver ,hallmarked.
I wore mine as a kilt pin.
It goes well too with chunky sweaters.
I bought mine from an antique shop.
£15 years ago,but it caught my eye.
It also looks good with very long sweater in arran knit which  I wear with slim trousers, the big neck looks better sort of draped to one side and held with this pin .
I love it ,had it many years now, nearly fifty.
Clean it and wear it.
, There is a hallmark and another mark too, one shape looks like a shield , both Glasgow and Edinburgh have used that at times.
I have a good Jewellers spy but can’t quite work out what is there ,
Mine has only the word Silver .
It is all shiny, clean yours up and I am sure you will like it .
If no silver Polish, try lemon juice and salt but really wash it well after.
 Euthymol toothpaste also cleans silver well
I wish you well to wear it.

Viktoria .