A fast way to empty stones from the board at the end of the game
Take the diamond off its hook, hold it by the top and the bottom and turn it over (whilst keeping it in tension). The stones all fall off, then you put the diamond back on the hook (still 'upside down') noting that the diamond is exactly the same either way up, modulo a 90 degree turn.
Notes on using the 'applicator':
There was a play-off in the design of the diamond when we decided how long to have each of the lines joining intersections. If its too small then you can't get your hand in, if it's too big then you've even less chance of working out what stones are connected to each other than you did before. I think we went for the right decision - with reasonably average hand size you can reach most intersections on the 84 model pretty easily (though the manual dexterity is part of the fun :), but you can see what's going on to some extent. The way to get to the harder to reach bits is using the applicator - basically a bit of (precision) bent wire. The best way to use it is to hold it almost vertically and put a stone on the very tip of it. Then approach your intended destination from below so it's easier to leave the stone on the intersection without disturbing it as you withdraw.
The 84 intersection board is, as we might hope, somewhat similar to a 9x9 board, in that there's plenty of space for a live group of each colour, but if you try to make 2 of one colour then you get into difficulties. I think it's probably the best size for starting out. The 165 intersection board should be near to playing on a 13x13 board then, by analogy, though I haven't played on one that big so I don't really know. I suppose the 286 board has to stand for the 19x19 niche, though just by number of intersections it's too small. The next size up is 415 though, which I'm sure is too big.
These are just what I've gleaned from playing a not large number of games on the diamond - I don't know how deeper concepts such as shape translate from 2D. Firstly, ladders don't generally work. On a 2D board you rely on using each of your stones twice in laddering a string of enemy stones, but the connections don't work the same way on the diamond. However, there is far more edge on the diamond. On the 84 intersection diamond there are 6 corners (have 2 connections), 52 'edge vertices' (have 3 connections) and 26 'centre vertices' (4 connections). This compares with 4, 28, 49 on a 2D 9x9 board. All this means that if you're laddering something near the edge it's generally pretty easy to drive it into one of the corners and kill it.
For similar reasons its harder to make eyes (different connectivity) but there's a lot more edge to do it in. These factors balance out to some extent.
Ko still works in a recognisable fashion, as do sente and gote. Its rather hard to wall off territory since its in 3D, but with more edge its easier to get '3rd line' (probably more like '2nd line') territory. Occasionally you notice something which has a direct analogue in 2D, e.g. linking along on the edge of the board - if your opponent cuts either side they get laddered into a corner.
Programs for playing diamond go
Diamondgo.exe - 47KB
This is a demo for windows which allows you to put stones down on an 84 intersection diamond, rotate it around etc. Thanks to Geoffrey Dommett for coding this.
The diamond starts empty - with grey 'stones' marking the intersections. You can click on a grey stone to put a white or black stone (alternating) down, and take off stones with a right click.
Arrow keys rotate the diamond. In File menu, New creates a new game, and Preferences lets you change the size of the stones. The other thing that works is in Window menu, where New Window creates another window on the same game, so you can see from a different angle. Be warned that this is a very much a bare bones demo from around 1999.
Take a look at Ishihama Yoshiaki's webpage for a Macintosh 3d go program.
A very flexible program by Lewey Geselowitz. It has support for user specified 3d boards, and internet play, on both PC and Mac!