Aquamarine is green; sapphire is blue.
When you say chartreuse, jade or viridian, you mean green. Right?
When you say cerulean, cornflower or cyan, you mean blue. Right?
When does keeping things exact
become making things complicated
(When you are a two-bit colorblind wedding coordinator who cannot, for the love of patience and worthless palettes, refrain from impressing neo-sadists a.k.a. couples-getting-married with a lot of artsy-fartsy quasi-knowledge. That's when.)