Hey Wilffndgold, Sorry i never got back to you have been swamped with work. Glad to see you made it out there and have started digging best of luck it seems to me like your on the right path. Finding those garnets is awesome, keep looking, with some that large i bet there are some smaller gemmy ones around. The mesa grande mine in socal, and i think the little ramona mine in socal produced gem grade, or atleast clearer colorful garnets. I tried to get out yesterday and dig, but the ground is already freezing up out here.

We got one really nice week left though so im gonna try and get out there, got a good tip and am close to getting permission.
So keep at it, your bound to get lucky in an area like that. If you can see if you cant find any geologic surveys of the area, and try and find out the direction that the pockets are moving in the pegmatite, this can be hard to find, but a good starting place is already existing mines, and older books 1900-1950s are usually good sources.
Mineralogy Database - Mineral Collecting, Localities, Mineral Photos and Data is a great source to use for mine info, search for the himalaya mine mindat, then go to maps and select nearest locality's and look at the tourmaline mines down there you can get some direction of the pegamatite formation and direction from them usually, and then try and guesstimate the direction of yours from theres. You might even be digging in the middle of all the mines. It will help you alot get to get a sense of if your digging in the right place.
With a place like that its all luck you might dig and dig and dig and find nothing, then move a rock you have been stepping on all day to find a pocket.
I was mining at the ace of diamonds mine up in herkimer NY earlier this year in September, and we where digging had moved 300-400 hundred pounds of material, next thing you know my buddys telling me to move that im standing on crystals. and sure enough as i was clearing small tailings with a shovel, the tip opened up a medium sized pocket of crystals and decayed calcite, and the crystals poured out right underneath me. So ya never know what you gonna find, you got a smorgasbord of minerals going on there.