Moissanite

I used to wear 6mm ball studs every day. Ball studs are nice because they're interchangeable if you lose one. Now I have bezel set garnet studs that sit flat (disc style I guess?) that I wear daily.

I wear solid 14k gold ball studs. They are small, like 4mm, but match everything because they are essentially a 'basic.' You can also get small gold knot earrings. Less than $100 but real that holds its value.

A pair of Tacori gemstone studs.

I have a co-worker who wears a micropave diamond disc studs that seems to go with everything. I like the disc stud look.

I wear small sapphire studs as my default earrings. I suppose they aren't as neutral as diamonds, but I like them. Maybe look for a pair of pretty gemstone studs that you like. Small hoops are also an option.

I wear small gold hoops daily. I think they look a little snazzier than studs. But if you prefer studs, just get some that are gold or white gold - much less likely to irritate your ears.

I have small aquamarine studs set in silver that I love. They are clearly not diamonds and aren't meant to be--they have a slight blue tinge. They go with pretty much everything.

I got a very inexpensive set of 6 pairs of studs from Amazon. Judging from the price they aren't the highest quality, but I've had them for several years now and rotate them and they all still look good.

After once losing an expensive diamond stud, I now wear cubic zirconia studs set in white gold most days. I do have to look specifically for white gold because silver and other metals irritate my skin with extended wear. I am not someone who likes a lot of bling for daily wear, but I don't find them too flashy because the setting is so simple and my hair obscures them anyway.

You can get some nice clear stone studs that aren't diamonds, but aren't cubic zirconium. I got some white topaz earrings that I can wear every day. They look great and I won't stress if I loose one. They're probably $100 - $150.

OP Here - I'm pretty frugal, and already have diamond studs so not sure I want to buy another pair.

And get screw backs so you don't have to worry about them falling out.

Small bezel diamond studs.

I'm still sporting the piercing studs from 3+ years ago when I had them done (for the third or fourth time). If I leave earrings out for longer than 24 hours my holes close, so I need something nice that I can wear daily, that won't change my ears colors or throw me into panic mode if one falls out. I have some nice diamond studs I wear on occasion but looking for something pretty plain for most daily wear. Suggestions?