Usually the titanium ring rough will be cut into whichever shape that requires the least amount of sacrifice. Marquise and oval shapes should have a length thats exactly twice the size of the width. If they are too narrow or too wide, the stone will loose light and appear too dark.
Extremely subtle color differences can be very important to determine rarity of a diamond dealers, but are never a critical factor in beauty.
The range of ideal cut diamonds prices can be dramatic depending on the size and quality. For example a half caret brilliant cut round diamond of K color and I1 clarity would cost about $2000 per caret or $1000.