Given the troubles I've had with lighter-toned Chanel shimmers before, my expectations for Mimosa weren't overly high, so I wasn't surprised when it needed three coats, was slightly streaky, and kept its shimmer hidden in most lighting situations. In my lightbox, it took on a decidedly lemony cast (i.e. sharp and bright and every so slightly green-tinged).
When I took it out in the weak winter sunlight (yay, we actually had some in my part of Michigan the day I swatched this), it looked warmer and flashed its shimmer more.
You know I love my comparisons, so I went to my nail wheels to find the most similar yellows in my stash. I came up with Revlon Top Speed Electric, Revlon Street Wear Taxi, and Sally Hansen Hard as Nails Solar Creme.
Note: Solar Creme is not really a creme; here's a close up of the bottle. Maybe Sally Hansen figured the shimmer was so shy they'd just call it a creme.
I used three coats of all of these, and all showed the same lemony inside, warmer outside face as Mimosa.
None of the dupe candidates were an exact match for Mimosa, but any would make a fine alternative if you have them. If you don't want to spend Chanel money on a yellow shimmer, Electric is still available in stores. I wish the Street Wears were still in stores; here's a closer look at Taxi, which was the best behaved of this group of yellows.
Polish Pauper also sent some fantastic extras with Mimosa, but I'll leave those as a surprise for later entries. (Looking at my "to be swatched" queue, probably much later entries.)