I have several early Mk2 and they are painted grey to almost black in color. At least one is grey with yellow traces. From memory, it looked painted yellow aver the black. These are Mk2 with the lead filling plug in the bottom, not the later Mk2 with the solid bottom. And their fuses are made of lead, unlike the later Mk2A1 fuses.
Early Mk2A1 were painted all yellow... (if you want to know why, I seem to remember yellow meant HE filling.) Of course, it was quickly found that a yellow grenade was not a good idea so OD colored grenades with a yellow ring (so it was clear the grenade was still filled with HE!) at the top was adopted.
Most, if not all, "pineapple" grenades you will find at surplus store are cheap Korean knock-off of the US made training grenades... The cast iron body is made in korea as a novelty item and the fuses are surplus M228 training fuses as used with the M69 "baseball" training grenade... BTW, the cast-iron bodied "baseball" and "lemon" type grenades also found in surplus stores are cheap korean knock-off as well as the real grenades are made of steel...
Hope this helps!