Truly collectible titles should be kept in their original cases as much as possible, especially if they're uniquely colored or marked. Even plain old black ones are often somewhat different from replacements, especially if they're really old. Many cases are embossed with the label's or manufacturer's logo or name. And of course, Ryko likes them coke-bottle green trays (believe it or not, they trademarked their trays). Also, replacement cases are usually less sturdy than originals; this is easily noticed by a collector.