I looked at your pics,
Andre21
, and don't see anything in them that would lead me to believe that your Turtle is anything but authentic. Shirogorov refers to the blade cutouts at the blade jimping as extracts. They were featured prominently on the F95R models when they first came out, but their origin goes back to earlier models like yours.
I really don't have a sense of a time frame regarding a switch from S30V to S35VN and I'm not sure that there was ever a specific change from one to the other as Shiro used a much broader palate of steels back in the day including the aforementioned, 440C, ATS-34, CTS-40CP, Vanax 35, RWL-34, BG42, Cronidur 30, and CPM 3v before settling into the more familiar and current M390, Vanax 37, S90V, and Elmax. Some of my Shiros go back a number of years and I have knives in 440C, S30V, M390, and Vanax 37. I do have a source that I can ask what years the Workshop did use S35VN if you're interested.
As far as COA cards, they're a more recent feature that I believe began in the 20-teens. The black vertical cards were only issued for knives sold through the one official North American dealer--actually the only official dealer worldwide outside the Workshop until Knifecenter became a subsidiary dealer and Shiro authorized one in Russia. Horizontal white COAs also began to come later with knives sourced from the Workshop. Custom Division and collaboration knives come with their own specific certifications. Knives have always come with a folded, stamped customs certificate that was often mistaken for a COA.
That's a nice looking, older Turtle you have there. Congrats on your acquisition and stop by, check things out, and drop some pics over at
The Bears' Den.