"Have used Emerald-Flat and Cashmere-Flat in the same room, same color. It's a long story about needing one more coat on the ceiling and not wanting to buy another full gallon of Cashmere.
Big mistake! Cashmere is AMAZING, the flat is so rich and saturated (I used Shamrock- a deep green). The last coat of Emerald was so 'flat' (I get the irony) and dusty. You can EASILY see roller lines, whereas my walls (that are same color, but in Cashmere- look flawless).
My advice is go with Cashmere, every time. Emerald is not worth the re-do's and headaches from a less than perfect finish!"