If you look closely at the ROCCAT Kone Pure Optical's software you'll find that the Kone Pure Optical features an LED-illuminated logo in theory capable of 16.8 million colours in RGB space. The utility allows the selection of colour in a 2D spectrum or selecting colour via its RGB value. Whichever colour is selected, the response on the mouse is bright and rich even if it cannot quite replicate all of them quite as accurately as you might want. The LEDs do appear to have difficulty matching particular colours with low intensities in a RGB field: a little (<5) blue in a strongly red signal will tend to appear more pink/purple than expected; a little green creates a strongly orange/yellow etc. That said, you should be able to achieve a pleasing result if you play around a little. Whilst perhaps not quite 16.8 million different colours, there are at least dozens and probably hundreds of colours to choose from.
As we mentioned the LEDs illuminate the ROCCAT logo on the rear of the mouse, but in the case of the Kone Pure Optical does it with a sharpness that's surprising. The bleed we noticed on the Kone Pure appears to have been close to eliminated on the Kone Pure Optical, although there's still some brightness variation around the logo itself. For those using the mouse with their right hand (the vast majority we would expect) the variation will never be problematic and may in fact reduce the chances of distracting anyone sitting adjacent to you. We're not sure if this was a deliberate design decision, but it's worth highlighting.
The mouse also features breathing and fully-off modes for lighting, whilst we've been able to discover that other modes are possible through early ROCCAT Talk FX software prototypes. Adding the ability to change the rate of the breathing pulse, or simply adding a means of flowing through all colours, would be a pretty cool; however as configured the effect is smooth without any significantly perceptible step transitions between intensities.
Colours are stored on a per-profile basis, meaning that a particular colour combination could be used to discriminate between said profiles. Configuring this to also vary on DPI would probably be too much of a challenge without adding additional LED locations, but it does mean that the only active indication of a DPI change is either the audio notification or you perceiving the movement of the cursor.
If the mouse is in ROCCAT Easy-Shift[+] mode the LEDs will be overridden to a light blue. At first we couldn't quite see the point, but when combined with ROCCAT Talk it makes troubleshoot that much more straightforward as you can assess what mode the mouse is in at a glance.
For a mouse in this price bracket the colour options are pretty good, and improve the functionality of the mouse to boot.
ROCCAT TALK FX
ROCCAT Talk FX is a propriety protocol which links the lighting of ROCCAT peripherals for the purpose of synced colouring and effects. It allows control of the underlying dynamics of the lighting and, if the API made use of in a game engine, can react to in-game events. In World Of Tanks for instance the lighting can be set up to reflect your current hit point status and blink when you're hit by a projectile; however it can also be use to reflect ambient on-screen lighting to increase immersion in otherwise low-light conditions.
Although the recent Kone mice all support ROCCAT Talk FX, only the Isku FX keyboard fully supports it thanks to a multicolour distributed lighting system. Keyboards with a fixed colour backlight, such as that present on most mechanical boards, are unsuitable for some of the aspects of Talk FX (although it may be possible to link non-colour lighting effects). In that regard Talk FX should only really enter into your decision-making if you own or plan to purchase an Isku FK keyboard.
You can find a discussion of Talk FX in our review of the Isku FX, but since then ROCCAT has make the Talk FX SDK more widely available through their download site. With enthusiast developer support its hoped that more complex tools will be created for this largely aesthetic feature, but until then only World Of Tanks actively supports it in-game.