If by "neelam" you mean blue sapphire, I'm sure that they can indeed be worn together, whatever you mean by that. A fine blue sapphire surrounded by brilliant white diamonds is a thing of beauty.
Any gemstone that is set in jewelry that is worn next to the skin usually has a hole in the setting, which allows liquid cleaner or steam to circulate around the stone to clean it. The gemstone so mounted does not have to be a genuine or precious gemstone, simply one that should be cleaned.
No.
'Nilam, Neelam, Neel mani' most worn for getting blessings of Planet Lord Shani.
it used as gemstone material(^_^)
Yes.
You may wear it where you wish
There are many styles of diamond rings created specifically to be worn on the right hand. Some places that one can purchase right hand diamond rings include Dazzling Rock, eBay, and Bonanza.
'Best' is a judgement, and you are the judge. Setting a diamond is motivated by the quality of the diamond. Your jeweler can best answer this question once you've chosen the diamond and decided how it will be worn.
'Good' is a judgement and you are the judge. A 'good' diamond could be a perfect, flawless, diamond, as in a 'good' investment. Or a 'good' diamond could be a family heirloom, worn by several generations of fabulous women.
A diamond stud implies that the diamond has been mounted in jewelery that can be worn in the ear lobe, in the nose piercing, or on the tie or lapel. A diamond solitaire generally refers to a single diamond mounted in a ring.
diamond is a friend of saturn and mercury so it must b worn on middle finger or little finger
Earring materials can be a diamond, but you'll need metal in order to mount the stone so that it can be worn in the ear.