You guys and your questions...driving me to research my archives (which I actually love doing)! OK, here's what I know.
This ad, displaying the new 1986 offerings, was in use by April 1986.
The new knives were the mini fixed blades, the Magnum Tanto, and the Shinobus. The Outdoorsman was already available in 1985.
The Shinobus were the first folders, and all three sizes had San Mai III blades when they were initially introduced. The Clip Mates weren't released until 1987, along with the Trail Master. The smallest Clip Mate was only offered with a 400 Series Stainless blade, while the medium and large sizes had San Mai III blades. I believe they later changed the Shinobus to this steel arrangement, switching the small blade to 400 Series.
The earliest mention of the Master Tanto that I can find is February 1986, though the article does not refer to the knife's San Mai III blade, oddly enough.
By April 1986, the Master Tanto and the Imperial Tanto (constructed of Damascus San Mai III) had been released. In none of the earliest photographs depicting a Master Tanto is the blade labeled as such.
I discovered that this catalog/brochure, the earliest on the Cold Steel Web site, has been mislabeled.
It is NOT from 1988, but rather from 1986. Look closely and you'll see that it contains 1986's knives, but nothing later. It doesn't even show the Imperial Tanto. The catalog mentions the Master Tanto, but says that a Master Tanto is not pictured. It does contain a photo and callout of the Master Tanto's San Mai III blade, however.
So what does all this boil down to? I think that around 1985 (perhaps earlier) Lynn discovered Japanese san mai
steel construction. He patented the San Mai III formula and introduced it very early in 1986 on the unlabeled Master Tanto and on the Shinobus, followed shortly afterward in Damascus form on the Imperial Tanto.
As for Ken's question about other san mai
offerings in the U.S., there were none that I know of, other than Mora's laminated blades, which were of course from Sweden and only referred to as "laminated." The first non-Cold Steel knife with a san mai
blade that I remember was Al Mar's Shiva, and I believe that was offered after 1986. As far as I know, Lynn Thompson introduced san mai
to modern America.
P.S. - jencarlos, nothing that I found identified the steel composition of the original San Mai III. "400 Series Stainless" probably covered several stainless steels with which Lynn was experimenting, trying to discover the best performer from the best manufacturer. But a 1985 ad identifies the Tanto's blade as 425 stainless at 56-58 Rockwell C.