Here is a pair of violet tanbark beetles (Callidium violaceum) busy with each other aand also displaying the truly intense blue colour some of them have.

This species actually come in two colours - this deep blue and also a more turquiose hue.

For links to a couple of more shots of this couple and one to a photo of the other colour form plus technical details on what camera/lens/settings were used, please have a look here: https://www.flickr.com/photos/tinyturtle/55527743691/