Featured The only antique&collectable I regularly buy in my country...

These particular stones with gradient shade are called egg white agate (but not much information available on them) and they are super rare and dear! The finest ones would look like:
And smell like a thousand pounds at cheapest.

 

I'm not touching that......

 

I think @Desertau will be interested to see these, he likes Chinese 'stone culture'.
China has a culture around stones that isn't understood outside China.
Such things are often local/national. For instance, we Dutch swoon over Mediterreanean red coral and traditionally associate it with healing properties, especially for women. In parts of Indonesia bezoars are highly valued, as are stones that are naturally shaped like 'Gana', spirits of nature. I have a keris hilt that is a black coral Gana, very special, but Chinese and Europeans probably see an ugly black knobbly 'thing'.

 

Around here there is a local rock called dallasite (named for the beach it was first found on) and flower stones and Chinese writing stones (same as flower stone, just a different configuration basalt and porphyry). Lots of other stuff, too, but walking on a beach around here you might come across this stuff.

 

Lovely, thought it was some sort of fossil at first!

 

Those are beautiful.

Indonesia has writing stones as well, I have one with my initial on it. But those aren't particularly sought after and they don't have the high value of Gana stones, they are just fun. I also have a bunch of Moluccan black coral and white coral bracelets, and a snake skin stone from Madura, Indonesia, but again, no high value, just fun.

 

Petosky stones are found near the USAian Great Lakes and they are indeed fossilized corals or the like. Greatly prized by some and unknown to the rest.

 

I think anyone who was a kid has a love for rocks. Beyond the collecting or precious type, I still have a bag of plain tumbled decor rocks that came out of something I got rid of, but I couldn't let the rocks go! It's completely dumb, but there's just something about a Good Rock.

 

That and old school Charlie Brown fans. "I got a rock." (Peanuts Halloween special. Now only aired via streaming, which sucks...rocks.)

 

The interior Pacific Northwest/Northern Great Basin USA, where I hike a lot has quite a lot of rocks to find like that. Geologically diverse, and a long long time ago, volcanically active.
I'm curious what aspects determine value where you are.

 

We collect rocks where ever we travel,Southern Washington carnelian.

 

Well it’s just what people want in all stones: size, shape, colour… but those with patterns resembling landscape will be particularly valuable

 

This is isn't the greatest example, but it happened to be sitting on my desk from a recent hike. There are places in the area that have some nice 'picture jasper'.

When I'm out, I'm usually focused on fossils, opal, gold, and quartz crystals.

 

Oh nice! We have a stone of similar pattern which we called dragon scale stone, but it usually comes in green. It's very rare!

 

Those rocks are so cool.