Yes indeed, that is gorgeous. Be careful with sun exposure. I moved a crested E. kibwezensis outside a little too early this year. It was seriously suburned on one side. Hopefully the scars will be less obvious as it gets older. Your plant looks perfect. It is growing on its own roots?

Looks like Euphorbia barnhartii to me. Here is a link that might be useful: Euphorbia barnhartii

If so it is for take the rot back scraping it to good tissue on the cactus when u get to tissue that ant mushy or soft stop put some good alcohol on the spots with a qtip and let it dry repeat the applying of alcohol two to three times then the spots should scan up for u in a few days stop watering it for about 4 weeks and then put ur finger down in the pot on the edge to see if it is still damp if so don't water till it is dryed out completely then only water a bit hope this helps if its not to late

http://www.dunecraft.com/resources/cactus_plant_information.htm "Gymnocalycium Mihanovichii Ruby Ball Cactus Originating in the Chaco Boreal in Paraguay, this plantÂs most unique characteristic is its color. The body of the cactus is grayish-green with red highlights. When the plant is exposed to gamma rays it loses its chlorophyll and becomes bright red. The plant is considered to be a miniature cactus. It only grows to be one inch high and has a two inch diameter. It was originally discovered growing under bushes where it was only exposed to direct sunlight a few months out of the year." http://home.att.net/~larvalbugbio/cactus1.html "This Paraguayan cactus is very common in the bargain baby cactus sections of most plant nurseries and it is also the species used to produce the red grafted cactus that is on normal, green stock. The red is produced by subjecting the normal cactuses to gamma rays to eliminate chlorophyll. The red version can produce flowers but not roots, and can't feed itself and so lives off the stock onto which it is grafted." And from the very site you cited: http://www.lapshin.org/cultivar/N2-3/colect-e.htm Read under "My new colored Gymnocalycium: From the seeds irradiated by ultraviolet rays". It states "The irradiation took place the third day after the sowing of the seeds. The distance from the quartz lamp to the soil was not more than 16 cm. The irradiation lasted 15 minutes. By the moment of irradiation the skin of some seeds had already burst. Further these seeds gave "colored" seedlings." www.lapshin.org/cultivar/N12/histor-e.htm seems to be the only page you can cite for your information. That page does not address "urban legends". Perhaps the Japanese developed something similar to the neon cacti we see in stores. These plants aren't just variegated, they're completely devoid of any chlorophyll. http://www.hi-ho.ne.jp/bk_ashiya/img/hibotan-n.jpg Here we see "Hibotan", a bright red cactus, growing on its own roots. The boldly neon colored ones can't do this. When you Google images of Hibotan-nishiki (nishiki meaning "tapestry"), many of them are growing on their own roots. Is it not possible that the ludicrously neon ones are only being called Hibotan-nishiki, and, in fact, ARE being irradiated? I quote from towards the end of the article you posted that said that Hibotan-nishiki were cultivated by Eiji Watanabe: "The above story has been widely circulated, but there are some doubtful points. In those days, origins were not revealed, and Watanabe was agood [sic] story-teller."