I've found that a nailclipper (compound lever type) of a size where the cutting surface is about the width of a thumbnail and has sharp corners, and is reasonably sharpened, can be used reasonably consistently to clip away at the seedcoat of lotus seeds by starting with the corner in the "dimple" end of the seed, allowing you to get to the cotyledon in about five or so clips (about 5 seconds). If you angle it right it's fairly safe (to both the cotyledon and your fingers). Of course, if the seeds are valuable then filing with a rasp or diamond file is a safer option, but the difference between clipping for a few seconds and filing/sanding for a minute or so does add up.
Here's the nail clipper I use, shown next to some clipped seeds and mug for scale:
P.S. not sure if this should be posted in another topic or not? Other plant/fish forums usually have a "propagation" or "breeding" section where I'd usually post this.
- Andi
