Oh dear, I can remember once asking about colour. Not colour match exactly, but asking if some little pearls (for cardmaking etc) were more a stark white or an off white.
The seller answered within about 15 minutes and I had to reply not to worry, after I had asked the question, I had just gone ahead and bought them anyway. I had thought what the heck, for $4 a pack or whatever they cost (I have forgotten exactly), if they weren't right it didn't matter and I would just use them on something else.
We actually got into a bit of a conversation, she was a lovely seller and the pearls ended up being perfect. She even sent me one spare sheet extra, which was unexpected but really generous of her.
Again-again, if it is a live auction outside of ebay, you may not have to worry too much. You certainly don't have to answer her questions but is it the sort of site where buyers can leave feedback? Are you able to block buyers?
Are you asking the same price, or at least higher than $19.99?
I can't see this person bidding on your live auction @ $29.99 if she never accepted the $19.99 offer. It isn't logical. But then again, maybe she's not the full quid as my dad used to say.
@springyzone wrote:
A simple question about colour isn't unreasonable, but it can be difficult to try and explain what you see, vs what your photograph looks like, especially once you throw in the possibility that the buyer might see a different shade on their own device. The best you can do is find a well-known real life comparison and hope your buyer pictures it the same way. If someone is really particular about a shade of colour, though, as in nothing but the exact shade they want will do, I will always recommend they go to a B&M shop so they can select from something in real life.
Colour matching is something a bit different, though, that definitely takes work and sometimes a lot more that it might sound like - I used to have these glass items that came in a random mix of patterns and colours, there was maybe about 7 or 8 different main colours but no two would be exactly alike, they'd just be the same colour and pattern. A buyer contacted me and said she wanted to use them to make earrings, and would it be possible to make sure there were matching pairs in the lot I sent. I said sure, no problem, thinking it would be a quick job. It wasn't 
It took me more than an hour to sort through enough to find ones that would match together. I had other people ask me to do the same, but I always said no after that (they were sold for less than $4 a pack, I might be more inclined to spend an hour prepping them if the price provided an hour's wage, lol).
