Hashish produced in Nepal, Afghanistan, India, Pakistan, and areas around the Himalayas is produced by rubbing marijuana flowers with the hands. They try to get the THC out of it. It is usually dark brown to black on the surface and lighter inside. It can be adulterated with almost any type of oil including coconut oil.
Middle East hashish from countries like Morocco, Turkey, and Lebanon are produced using the sieving process. It is usually hard and can vary in color from yellow to red. If you break a piece open, you should see granules of resin that make up the pieces of hashish made by sieving. It can be adulterated with a variety of things like tar extracts or henna\tarmac.