I'm pretty new to this, but I have a nice almond wood slab that I'm turning into a coffee table. I basically want to achieve a nice, penetrative, high gloss finish on the table (it's a live edge slab). I'll be putting hairpin legs on it and going for that modern 50s live edge slab look. I've read many, many articles on the subject and I'm quite lost - should I use a polymerized tung oil, or a polyurethane varnish? Shellac, perhaps? How fine should I sand the piece? I've done sandings at 120, 180, and 220 but I have no idea how far up I should go - I don't really want to sand out 10 different grains and run three or four coatings on each grain. I'm just looking for someone to help me set the boundaries a bit.

It's a 1700 on the janka hardness scale, in case anyone is wondering, and has beautiful gold and faint purple colors running throughout. If someone could give me some basic guidance for a high gloss finish that would really demonstrate the beauty of the grain, I'd appreciate it.

There's really no exact answer to your question. If I'm doing a high gloss finish, then it will either be a marine-type varnish or a two part linear polyurethane: two very different finishes, requiring different skills, equipment, and processes. In either case, you'll loose those purples, but time will eventually take them out anyway. The best bet would be to find a finish that you like, find out what it is, and focus your efforts. There's no best finish, but any good one requires developing a skillful way of working it in addition to aquiring knowledge about it. So, don't sweat it, you're at the learning by doing phase.

Do you have kids, or going to have them? A brother that puts his feet on furniture? Like to eat and drink by the coffee table? A young Lab dog that like to lick spilled food off the table, or chew the corners? All these will require the toughest finish you can get if you want it to look clean for a long time. If you want it to look like a piece of timber, and enjoy the look of wear and tear, then just oil and reoil every year. By the way, did you check the box about being a professional woodworker to list questions on this site? Notice the title of this section, Professional Furniture Making?

I would not use shellac as it is not moisture resistant. Polymerized Tung oil is a good choice and after about 5 coats you would have a nice glossy finish that is water resistant, durable, and easily repairable. You can also use polyurethane in whatever sheen you want and thin is down to a 50/50 mix with mineral spirits to achieve a penetrating first coat. From there you can build it with several more coats. Both finishes are wiped on with a rag. Keep in mind that a true high gloss finish needs a thick build of coats to be rubbed out at the end, so you may want to brush on the poly for that. As far as prep, sand the piece to about 180 for a penetrating finish and 220 for a topcoat finish. Lightly sand with about 320 between each coat of finish regardless of what you use. If using Tung oil you can wet sand the oil into the wood for the first few coats followed by several light coats and get a really smooth finish. Basically you are going to have to try and learn from each experience. But we have all been there. Whatever you do try each coat on the bottom first to see what results you get before to do the top.