Irish brooch age?

Hello to all, I found this interesting brooch in my travels today and had a few questions about it.
It seems to be some type of brass Irish brooch. It has the word o'coileain at the top, which is an irish name, or surname.
It is very large, it measures 5 inches wide by 3 and 3/4 inches tall. I seen some similar online but none were flat like this one.
The clasp on the back seems to look older, so my questions would be:
Can anyone put an approximate age on it?
Should i clean it with brass cleaner?
Is it just a modern reproduction?
I would like to thank everyone for the help in advance, as always keplnul the great work!

 

Someone more knowledgeable will be along, but I would not advise taking brass cleaner to it. A shine cloth would work well on this, I think. It does not look corroded or very dirty at all. The detail is fine and it would be a shame to take a harsh chemical to it.

 

Modern Tara Design Penannular Brooch..... https://www.harpanddragon.com/penjew.htm

 

I've an almost identical one. They're based on the Book of Kells. Yours is a bit younger than mine, the back looks 30s, but they've been made as souvenirs for decades. I'd only use a Sunshine cloth on it.

 

Thanks for the info

 

I'm with Holly, it is based on the Tara brooch. Which has nothing to do with Tara btw, it was the name a seller gave to it.
With a clan name on it, I imagine they would be sold in clan centres and souvenir shops.

Tara brooch:

 

aj, I did actually find a similar image to mine in the Kells images. I'll see if I can find it again.

The name is the Gaelic for Collins.

 

Correct.

 

"after" Irish cloak fibula.