OK so I was wrong about S&W being nickel plated in the 1860's. They were still doing it before Colt. The Belgians were nickel plating in the 1850's.
No, you were not wrong, sorry if I gave that impression. I was just showing a few plated Smiths in my collection. I should have been more thorough.
Let's look at this photo of three little #1 Tip Ups again.
The one at the top, a 1st Issue, 5th Type, usually had sliver plating on the brass frame, which has practically all worn away now.
The one in the middle, 2nd Issue that would have shipped sometime between 1860 and 1868, was available either with a blued barrel and silver plating on the frame like this one, or it was also available fully nickel plated.
The one at the bottom, a 3rd issue that shipped in 1870, was available in three different finishes; blue, nickel, or a nickel frame with blue barrel and cylinder. Mine is the nickle plated version and it shipped in 1870, however this model was made from 1868 until 1881, so it fits your criteria of being a nickel plated S&W revolver from the 1860s.
This is a #2 Old Army. This model was made from 1861 until 1874. Being a 32 Rimfire it was bigger and more powerful than the little #1 revolvers that fired what we would call today a 22 Short. It was not as powerful as the big 44 caliber Cap & Ball revolvers of the day, but it was popular with Union officers because as a cartridge revolver it could be loaded much more quickly than a C&B revolver. This one shipped in 1870 and it has the standard blue finish. However the Standard Catalog of Smith and Wesson states that an estimated 10% of this model were nickel plated.
That's it for the S&W revolvers made during the 1860s, the Top Breaks did not appear until after the Rollin White patent expired in 1869.
This is a #3 First Model Russian. At first I thought it was in the white, but later I realized it has been nickel plated, and a bad job at that, clearly an aftermarket plating job. It has also had a coin substituted for the front sight. This one shipped in 1873. However, this model is physically identical to the American Model, the only difference being the cartridge they were chambered for. The American Model was chambered for the 44 S&W American round with a heeled bullet, the 1st Model Russian was chambered for the 44 Russian cartridge. I do not have an American Model in my collection, this 1st Model Russian is the closest I have been able to come with its obvious flaws. My point is, the American Model, which was made from 1870 until 1874, and looked just like this, was available with either a blued finish or nickel plated. Several years before Colt began nickel plating the Single Action Army.