Scota4570 is right. But DMT makes diamond stones up to 8000 grit. Strop with leather glued to wood. For jewelers rouge use Zam. Don't use the red rouge. Red is great for gold and silver and such, but does not work on hard metals. But what works a whole lot better is 14,000 grit diamond powder mixed with grease. That will get your chisels very,very sharp. You can get diamond powder up to 200,000 grit, but no point in using is for sharpening steel. After 14,000 anything finer is not going to make a difference.
Just as important is to get good chisels. The harder the metal, the sharper you can get it. Think of how sharp you can get a pine blade compared to one of those diamond blade scalpels that surgeons use. Problem is that harder blades are more brittle. They chip easier. So they start making them of different alloys and tempers and such to make them more durable. And expensive. You can get a set of a dozen carving chisels for about $10 on Amazon. They work great for mixing paint. I really like the Pfeil chisels. Those are probably the best ones that you can get and they are worth every penny. Lots of pennies! They cost a lot. Get one or two every pay day and eventually you have a nice set that your grand kids will be using into old age.
I learned how to sharpen freehand. I tried one of those jigs once and I hated it. Got in the way more than anything else. But I know a lot of people like them. Jigs are probably easier to learn with, but freehand is better if you are good at it. I suppose it all comes down to what you get used to.
One more thing on strops. Get a bunch of different size wooden dowels. Wrap them in leather and glue them to a board a inch or so apart. Use that to strop the inside of gouges.