Is, probably, the most common mistake among coffee enthusiasts.
When someone is talking about Supremo coffee, they are not talking about the quality, neither the variety. They refer to the bean size. Before coffee is roasted, the beans are separated by size. This helps to have a homogenic, perfect roast, which makes you enjoy a better cup of coffee.
When the beans are separated in Colombia they are categorized by screen size. Supremo represents the screens 18 and 17, then we have Excelso that represents the screens 16, 15, 14 and 13. Excelso is separated in other sub-categories as well.
Many cooperatives around the world sell Supremo beans like the best variety you can get, which is a big lie to the buyer. The majority of cooperatives blend different varieties to have this Supremos beans.
Next time you buy coffee have this information in mind.