The purpose of this little exercise is to simply explain how I had created the picture Melting Rocks and how I can obtain bluish or dark background on macro pictures.

From here, you should follow this path:
i - Context – The scene
ii - Context – Bluish background
iii - Technical elements – From picture 1 to 7

Notes:
-I usually take macro pictures with my trusted Sony f717.
-The pictures with an asterisk '*' were only resized and compressed with Photoshop CS.