Matthew,
I was actually on a flight home from Boston when I saw this thread surface to the top of the board again, and I always get excited to see what someone is posting about hickory golf - especially if they want to discuss Tom Stewarts. Now finally home, I wanted to respond...
Regarding niblicks with Stewart inspection dots, I haven't seen a lot of them to be honest. I read once that approximately 2% of the total clubs Stewart's forge produced had inspection dots - which denoted they were supposedly personally forged or inspected by Stewart himself. At the same time, Stewart's forge was one of the most prolific of the era – at the height of production his forge, just a quarter mile from the Old Course, was producing 3,000 to 5,000 head per month - so while rare, they are out there - albeit commanding hefty premiums these days in the market.
Below is what the famed writer O.B. Keeler penned about inspection dots in his "Out of Keeler's Golf Bag" newspaper column...
"And when Old Tom Stewart personally inspects a club head and finishes it off there's a round dot punched into it. You might look in your set and see if any of the T. Stewart irons have a round dot punched into them. Probably not. Those I got from his shop didn't have it, but they were marked 'special'. However, Bobby Jones had a lot of copies made of his favorite clubs and I noticed they all bore the little round dot, which means that T. Stewart himself finished them."Below is a photo of one of my niblicks which does have the inspection dot, this is a set I purchased from Ralph's collection...
As Mr. Tigerman mentioned, there are a couple of dot-punched niblicks documented in Ralph's book - my club on page 174, and a particularly nice RTJ niblick on page 277 - that was produced for A.W. Armour of the Armour Meats Company. There may be others, but I didn't see them in my quick flip through tonight.
As it relates to your second question, I have only seen one red-colored pipemarked Stewart - that was on eBay a while back. I am pretty sure it wasn't rust, as the color was quite rich. I don't know anything about these and assume the paint fill was done sometime after the club head left the forge and was completed by the owner due to personal preference.
Hope this helps and always a pleasure to pull out Ralph's book, look through my Stewarts and talk hickory golf...
Chris.