Ya I wouldn't recommend going to a source country and Columbia is known more for cocaine anyways. #4 is commonly referred to as east coast powder and it's found all over the east coast and in plenty of other locations such as Chicago. Again, just because it's white doesn't mean anything. It could be cut to shit orcut with fent like Tommy said and both are pretty undesirable. Most east coast powder is more beige than anything although the color varies.
I'm starting to think that you're asking more if there's powder dope in the states that is of high quality. If that's your question then the answer is yes definitely. If you're looking for good dope based on the source and the color then you're going about it the wrong way. Neither are definite indicators of quality. Great dope is great dope and it can be white, gray, dark brown, beige or even tar or powder. Unless you're writing a paper or doing some research there is no real reason to seek out heroin of a particular origin.
The literal China white would be insanely difficult to fine but there it's great dope all over.