Need Help With Dirty Mtt 1780 Coin

Hi
I have this MTT coin and according to some topics here I cant Determin the time or place becaus its kind Strange about the marks on it like
1- no s.f. in the front just a I.C.F.A in back
(I have read that its a private version what dose it mean)
2- 1-3-1 Feathers Order
3- 7dimond in the crown
(Maybe 8 not sure)
4- oval brooch with 9 dimond
5-AVST.DUX. not AUST.DOX.
(Cant tell the diffrent and wich one is the old)
6-the "X" mark under magnifying glass look like tow leaf crossing

I want to know any info about date,place, price , is it a Precious coin
And can I clean it if yes how to,and dose the cleaning will effect the price.
And here the photos maybe it tell more about it