Fade to blue

I was wrapping up a nice Diplomystus for a customer when a woman asked to see a pendant in the cabinet. Riley had stopped in, so he opened the case and handed her the jewellery. I was still talking to the fish-buyer at this point, but could pick up the conversation in the background.

'So -what is this? It's a lovely colour.'
'It's a dyed turquoise from Arizona. They call it turtle turquoise.'
'Dyed? So does it fade?'
'Well, I don't think so.Um. You'd be be better asking Matt, there, I think.'
'This is dyed. Will it fade? What colour did it used to be?'
'We've had some of this material for a few years now, and I've not noticed any fading - it's not likely to fade any quicker than any other stone. It was most likely just very pale turquoise that they might not have had a market for. Quite a lot of the stuff sold as turquoise is really just dyed howlite. But it's pretty stuff, and dying it makes it of some use for jewellery. If you were to leave it out in bright sunlight for a while it might fade, I suppose, like many naturally coloured stones.'
'But will it? Why did they dye it? It's such a lovely colour - is that because of the dye?'
'...I think so. Yes, probably.'
'I'm going to get it. It's lovely. I just hope it's as nice in ten years time.'
'Me too.'