It's a beautiful piece however I don't see it as an applicable addition to the tattoo industry. The colors first off are based off the digital color range which can be up to a million (yes million) variants of the basic rainbow. Many of which are indistinguishable by the average human eye and even more so are not available in ink for the tattooist. If anyone were to take this to at tattoo artist and have it done they would be sorely disappointed as it wouldn't look anything like the picture here.
However as line art it's definitely possible and totally something worth looking into. If you could give a black & white line pdf to an interested party they could take that to an artist and have the basic shape done with the coloring being done to the tattooist's best abilities.
The only downfall I see is the little amount of knowledge you may have of the tattoo world, like the white you used for highlights is almost non-existent in the industry if it is used it fades rather fast. (often before the tattoo itself is healed) Other light colors like yellows and your neon-green don't usually take to skin on the average person as well. If you updated the image with some more basic tattoo colors an individual would have a more realistic ( I hate using that word) expectation of what their tattoo should look like.
Over all I think it's beautiful and might do better as a mural on someone's wall.
I really love the colors so much. I love how it's just not one but all of the colors mixed in together. The blending is incredible, it just doesn't color block one another which is a feat in itself. The dragon is also beautiful, I could never make a magical beast without help lol. It's interesting that you didn't put a background, I wonder what you would make for it, would it be just the plain sky or a mountainous landscape, or maybe the dragon coming out of a volcano perhaps, I wonder. But all in all this is a beautiful creation so kudos to you.
I am making a wallpaper for the wisp skin of the Rainmaker application. I was wondering if I could use this in the design and upload it to deviantart. I would, of course make sure to give you credit for the design. I already have the wallpaper made, and am currently using it personally, but I would really love to upload it to deviantart, as it is definitely one of my best creations.