I was wondering how different light sources expose inclusions. For example, will sun on a clear day wash out light return on a diamond to reveal, SI2/SI3 inclusions? How about 60watt light bulbs, or fluorescent kitchen lights. I was looking at an SI2 diamond at the mall today. It was eye clean inside the store. Under the scope, I very clearly saw the inclusion. It was a feather. Will certain lighting conditions reveal feather inclusions more so than others.
I suppose direction of the light will also matter. I won't mind an SI2 just as long as its eye clean under 90% of lighting situations. Please don't say "don't go below SI1" that's not really what I'm asking for.