This striking Sonerila has recently become available out of SE Asia. I will add more information when I have more experience with it. For the first few weeks after import, it was especially sensitive and went completely limp a few times. After heavy soaking of the sphagnum, it rebounded and now seems more stable.
A cutting rooted in clay below, taken as a small cutting off the mother plant. It rooted within one month in clay. For a species prone to collapsing from dehydration the clay is ideal because it forms a tight barrier of moisture around the stem. I’ve seen this species rooted from stem and leaf cuttings in a sphagnum mixture, but when I tried it, the cutting died within a week.
This species is making the rounds, now that there are shippers legally exporting out of Asia. There has been talk of it being Sonerila maculata, but the iridescence on that species looks to be more more exaggerated. It looks similar to heterostemon to me, but, it’s hard to say. That identification is based on an image taken by Patric Blanc, in this image gallery. His galleries are an excellent resource, and very inspiring!