Victoria 1847 Proof Gothic Crown Plain Edge

Due to the very high value of genuine Gothic Crowns, it should come as no surprise that they are very often faked.
Very attractive design and rare, 8,000 minted.

Coin looks perfectly OK to me, but in reality, that won't be of much help to you. I readily admit that I don't have the required specialist experience with Gothic Crowns to detect fake or not from screen shots, despite my decades of general collecting experience.

So, I searched Google Images to find out more about them.
Lots of very deceiving fakes are die struck from dies made by die transfer process from genuine coins. These fakes are also .925 fine sterling silver and are of correct weight and diameter

That means check weight, diameter and XRF testing for metal alloy, may not be of much use.

After reading comments in my search, it seems the best way of detecting these sorts of die struck fakes is to take the coin in question to someone who is experienced in their examination. An international auction house would have this kind of expertise. One important question that an auction house may ask about is an independently provable provenance, such as past auction records.
Another version of this approach is to submit a suspect coin for slabbing, and ask for authentication and grading in your submission.

I do this all day as a variety error collector. It also serves well to distinguish copy from authentic. I am by no means an expert and to go by pictures alone is not exactly accurate. Many things like lighting angle of the coin can make identical details look strange and out of place. So just to be devils advocate here I will voice my concern . If you look very closely and you will need to look a good few times so your eyes are trained to notice the minute differences in strike quality and design size. You will notice on a genuine gothic crown the lettering is thin and tight but has some very subtle curves. The coin featured in the post all the lettering is very mathematical as in every part of the serifs and the letter design is of straight lines and angles and is thicker as are the various colons and design jewels. As you look more and more you can actually see the clumseyness in certain areas where they had no room to make the exact same copy the left shield just as an example has almost no surve at the bottom and has been fiddled to make it fit the design . This has led to almost overlapping of the shields where they shouldn't touch at any point. Prob the bigest fopar is the jewels in the right shield below the crown the other jewels in the other three shields have a diamond shape and a centre jewel but the shield @ 3 oclock has a design of 5 tiny jewls and a centre jewel.
An oversight by the copier? he has continued with the oval diamond shape and a centre jewel. The eyes on the lions don't sit right with me either All is conjecture also this has the n/n inverted which is only seen on the .999 silver proof and is seldom seen. but for me without any known provenance It has to be sent away for verification I wouldn't purchase such a beautiful coin without it and until I see it slabbed I would side with it being a modern strike if its the coin it is supposed to be the .999 silver proof it will weigh 27.87 grams. I hope I am completely barking up the wrong tree but there are concerns in my book

Things got a little too spicy for the pepper as Francine Smith would say.