Mira moissanite is your best bet if you want a whiteish stone, durability, sparkle etc. BUT it's not a natural stone, it is man made. I would go for Zircon if you want natural.
I hear what you are saying. I've lived it!
I love wearing natural gemstones, and for a period of time could not afford the diamond earrings I wanted.
At the time, I could find blue zircon but not clear zircon earrings so didn't go in that direction. I have a white sapphire and knew that wasn't the look I wanted (clear glassy but none of that amazing dispersion). I also got a pair of white topaz earrings (white but with a bluish tinge) which I wore alot but it was more like wearing crystal than diamond earrings.
I purchased sarovski (sp) crystal earrings, and those were fun. I also considered moissanite but felt for that price might as well save the money for the diamonds. Also in some lighting I think the dispersion is almost clown-like.
In the end I went full circle and ended up getting a pair of high quality cz earrings. They are a realistic size and set in 14K gold so they felt good when I was wearing them. And when I saved up enough money, got a very similar sized pair in diamonds.
I do have some demantoids and they are gorgeous, but you can't get around they are green (I like green so that is fine with me!).
At the time if I wasn't so fixated on a diamond lookalike, I think I would have gone with a pair of morganite earrings because I saw some that were quite beautiful (they have a soft pink color), and personally find colored zircons (blue, or honey) more attractive than the colorless variety.
Another thing to think about is, what other earring that you like and can go with everything, and doesn't necessarily need to be a gemstone?
For me before I got my (first cz, then diamond) studs I wore a 14k yellow gold ball stud earrings, and also pair of round drop pearl earrings. If I wasn't specifically picking out earrings to match what I was wearing, those two were my go-to earrings. For my mother it was a pair of gold hoop earrings. Just wanted to expand your options in case you are like me and nothing quite filled the bill.