A friend of mine picked this up a few months ago at an estate sale and wanted to know if it can be restored and still get a good grade if he has PCGS restored and recapsulate it with a grade. Sorry about the duplicate photos.
It's only about 35% silver, the rest nickel and manganese. There were 120 million minted, so don't put much effort into "reshining" it. As above acetone or some silver cleaner to dip it, and you shouldn't even think about certifying it or having someone clean it for you. The cost to have anyone else clean it up would/will be over 10 times what to coin will ever be worth. Just keep it as an oddity.
The cost to conserve will outweigh the value of the coin many times over. You can try a little acetone, not mail polish remover, but pure acetone.
As noted, conserving the coin may be of interest, but TPG activities and costs are out of scope. Do a search here on coin conservation...you'll find many valuable tips. Using the least damaging to start is my suggestion. As some have noted here at CT, soaking in distilled water is a fine place to start. Timing and cycling should be kept in mind, especially as you escalate the process/materials. Our Ancient coin collectors here likely have the most experience. At some point, conservation gives way to cleaning, which generally diminishes the value and interest in a coin. You can bet the TPG will notice.
The answer to your question "Can it be restored?" largely depends on what is wrong with it. If it is just a surface film, a spot of something on the coin, the coin can be conserved - that is, the film or spot can be removed. I'll let others describe the methods. However, if that spot is actually corrosion and has damaged the surface of the coin... no, there is no way to restore that and have it be acceptable to the majority of collectors. For extremely rare coins, there are techniques to minimize the visual impact of the problem, but it will always be a damaged coin.
The black spots in the middle of big brown spots are probably beyond repair. As someone else mentioned, The Silver War Nickels are made of an odd alloy which is very prone to spotting. When these coins were first issued, they were bright with an attractive silver color. Some thought that would last in circulation, but it didn't work out that way. They quickly became dull with a brownish cast most of the time.
Greenish-brown, at least to my eyes. They really stand out in a pile of other circulated nickels, although regular cupronickel coins can sometimes tone to a similar shade.
All the above suggestions for trying to clean up your coin are applicable and should be attempted in very slow strokes. However, when I first saw your coin pics, they were really too blurry to see enough to even partially grade. However, you should be aware that the MS-70 grade is FAR from being accurate. Here is what I pulled off the internet for SGS grading: SGS (Star Grading Service) is generally considered a low-tier or "basement" slabber, not a reputable third-party grading service, known for consistently overgrading coins, often assigning MS-70 or high Mint State grades to inferior coins. Their grades are considered unreliable; coins in SGS holders should be treated as "raw" and valued well below those graded by PCGS, NGC, ANACS, or ICG. Reliability: SGS is not recognized as a legitimate, independent grading service by most collectors. It is often described as a, "self-slabbing company" where the seller grades their own inventory to inflate prices. Grading Standards: SGS typically focuses on grades 60–70, with many, if not all, coins listed as MS-70, which is highly unlikely in, "the real world". A coin graded MS-68 by SGS might be, "actually only AU-50" by standard grading definitions, according to The Voss Law Firm, P.C. and.
I’d keep it in that slab just because the slab itself is different. Some people collect slabs. I, like most others, collect the coin. The coin is going to grade high enough to warrant trying to get rid of those spots and it most assuredly will not be a grade above MS-64.
Never assume that you can "fix" a war nickel. That odd ball alloy of 56% copper, 35% silver and 9# manganese is not as stable as the 90% silver, 10% copper alloy. It can't be "fixed" at least not for the long term.
You can use acetone on silver coins or distilled water. You might not like the results though. There was gunk on the back of a Barber quarter and I soaked it in acetone and there was a stain or corruption under the gunk. I think I would rather have the gunk.
