Ah, then you know the area! Jade cove is next to sand dollar beach. There are two little rocky beaches there, one much harder than the other to climb down to. One has to hike out to a point and then scale down the cliff to the beach. But the jade can also be found on other beaches around there. My husband once found a piece of vonsen’s Blue jade on a beach north in Pointe Reyes. Ended up making a ring out of that one! Jade hunting is lots of fun in California. The scenery is beautiful, you get good exercise, and can take a nice picnic or eat at a local nearby. I’ve been told that the best pieces are found while diving/snorkeling in the area.
Re the star sapphires, often they are found in Sri Lanka, Burma and in other places. Every where that sapphires are found, stars can be found too, even rarely in Montana! Though, they are much more rare than sapphires. For every 100 gem quality mined sapphires, one star is found. Of those, only 1 in 100 is nearing gem quality. With stars, like jade, it is a balance of qualities which makes the stone. Too much silk, and the stone becomes opaque and color is affected. Too little, and it may not have a full star, or it has a weak star. Then one factors in things like inclusions, zoning, centerednessvof the star, whether the star has all legs, size etc. anything above 5 carats becomes exceedingly rare. This is why they are often not seen in mainstream jewelry, because jewelers could not secure enough of a reliable supply. One of the few jewelers who saved stars for designs after decades of collecting them is Oscar Heyman.
One has to be aware today that the market is flooded with synthetics and titanium stars, which are stars cooked into surfaces of either natural or synthetic cabochons. Thankfully, those are easy to distinguish. Not so easy is lead glass filled stars, especially star rubies. But also somewhat detectable by a high powered, gem microscope when the sapphire is translucent, and when you know what to look for. Opaque ones really need to be checked via lab. These treatments are relatively new, so if one buys an antique star, one is able to ensure that the star may have, at worst only been lightly heated. (Too much heat would dissolve the silk Since it melts at a much lower temp ). Or, buying from a reputable seller ensures a good quality authentic stone.