How to remove stains and discoloration from bluestone

https://www.yarrabeestone.com.au/blog/how-to-remove-an-oil-stain-from-bluestone

Since this is a natural stone which is porous, you can try a poultice to leach out the stains. Here's a you tube video: https://www.youtube.com/watch?v=5e1CO7HmFJI

If that doesn't work, you can lightly sand the stone to get the stain out. You need to use a penetrating sealer on the stone to protect it from these types of stains.

First try pressure a washer. Put a dish soap mixture on the stain for a few minutes, 10 or so, then pressure wash it. This will even get oil stains off a driveway.

If not inherent in the stone - try wetting it with soapy water and then pouring something like Shake and Vac to draw it out......

Dawn dish soap! The platinum kind. I just did my in laws porch with it, there were little oily looking spots where the boys sit and play. I used a tough scrub brush and rinsed it away with the hose

https://www.youtube.com/results?search_query=remove+stains+from+bluestone

Remove rust stains from concrete. Mix together a few drops of water with a packet of lemon-flavored Kool-Aid. Use a brush to scrub the stains away. The abrasive paste plus the citric acid can do wonders for your driveway or patio. Mar 28, 2018

This might work. But I would contact a place that sells the Bluestone.

Sulfamic acid