While Ubuntu MATE provides support out of the box for Folder Color, the MATE icon theme doesn't seem to include the proper folders and it uses the default icons provided by FC. They're quite similar to the 17.10 theme but they're glossy.
Are there plans to complete the MATE icon theme? If not, I can contribute.
EDIT : I made the color variants, not sure where I can offer to include them (Launchpad? GitHub?).
EDIT: opened a bug report / wishlist on Launchpad.