Can you take a photo from farther back? It probably is just the natural variations of granite, but that picture is so close-up, it’s hard to see.

Also, many granites do not need sealant at all. Granites vary in how dense they are. Some granites are so dense that nothing can penetrate (iI.e. stain), and those granites do not need to be sealed.

Here is the full island. The brown / black pieces are the pieces that are dull/raw looking over certain light and don’t have that gloss look.

Looks like natural inclusions in the stone that are harder than the rest of the surface and too hard to polish. It happens, that is mother nature.

You've got stone with a lot going on in it. Some pieces are going to shine more than others.

That is a granite called Bianco Antico. A very durable and beautiful stone. As has been already mentioned, you are just seeing variations in the granite that are natural. You are lucky to have such a durable stone, as there are many out there that stain or etch - yours will not.

You may not have to ever seal that granite. The way to test if a stone needs sealant is to drop some water on the surface. Wait 10 minutes. If the water absorbs, the stone needs to he sealed. If the water is sitting beaded on top of the stone, it does not need to be sealed.

Thanks so much!

It might also be a filler that was applied to any indentations/cracks/gaps in the stone when it was polished at the quarry. Here is a filled section in my Taj Mahal quartzite. They usually pick fillers that blend in, but they definitely reflect light differently. All normal with natural stones, specially the more brittle ones.