This is only a start, but as more "RAL8000" parts become available in the US, I -- and I suspect many of you -- have started tracking the many shades of RAL8000. While this still is a developing story, based on my recollection and my review of Google pictures, I've compiled the following table and visual glossary. It may not be authoritative, but at least its a start. (Obviously, different cameras and different lighting greatly affect representation of these colors in photographs, but I think generally these categories are legit.)
The table uses "brown" to denote the dark "chocolate" color first used when the HK416A5 began appearing a few years back:
The table uses "burnt bronze" (Cerakote H-148) to denote the somewhat lighter form of metalic brown that is common now on HK weapons, but is clearly not RAL8000 as seen on the pistol grip here:
The table uses "green" to denote a similar form of metalic color, but one which is more green than brown. So far, I've only seen it on the HK416A5, and then, mostly on rails. In fact, I think another HKPro member has such a rail in this particular shade of green up for auction on GunBroker. Here are some pictures that capture the difference between the burnt bronze (upper receiver) and green (rail):
The table uses "RAL8000" (Cerakote H-8000) to denote the yellowish-brown color that is often described as similar to baby poop.
Of course, this category by itself is quite broad on its own, as HK has been all over the yellowish-brown map with parts of late (stocks, grips, rail covers), sometimes even within the same part. Currently, RKS Plus is having a fire sale on mismatched SlimLine stocks:
So like I said, this table is just the start. To date, I haven't really found any rhyme or reason between the various colors HK denotes as "RAL8000," or even between the various shades within the yellow-brown of RAL8000 that HK uses for parts. Within each category where more than one color appears, I have listed the most commor color first. As folks move beyond basic black to accessorize their weapons, hopefully some will find this table of use: