Here is a really cool product from Iwasaki, it is a led bulb that looks about as close to HID as I have seen. It uses the same BT shape glass envelope as their HID lamps but with led diodes inside. I unfortunately have not seen anywhere that these are easily available here in the US. here is a video on this rather new product.

https://www.youtube.com/watch?v=I5ATR4N6i14

Wow those look so cool, usually the thing that gives it away for the coated ones is that they are coated all the way down to the base, but these must use literally the same exact envelopes as the HID ones. Never seen BT shape retrofits either, that is just so cool. Very nice find, I also have yet to see them for sale.