One of the things that lets the world know you are very serious about your home bar is what professionals call -- without the merest trace of irony -- your "ice program."
What this really means is that the ice you use has no crazy off-flavors, it dilutes your drink neither too much nor too little (i.e., The Goldilocks Principle) and enhances the appearance of the drink in your hand. For Tiki drinks (please consult my published works) crushed ice, or sometimes very small cubed ice, will be fine.
Tiki drinks are usually opaque and/or served in opaque vessels and/or are garnished VERY distractingly, so the ice doesn't play a terribly important visual role.
But, sometimes you are serving something "on the rocks" or similar. It's a clear drink, so the ice will show. You want this to be attractive...maybe even a bit dramatic. So you get Dramatic Ice Molds, to yield either a giant cube (as above) or an ice sphere.
For this you will need an ice mold. I suggest that you get one of the freebies Maker's Mark sends out when you become (again, free) an "Ambassador" on their website.
The other thing is that you want to have your ice as clear as possible. I'm not that fanatical, so an opaque core doesn't vex me. At any rate, the trick is to direct the direction of the freezing so as to minimize the amount of cloudiness trapped within the ice. You do that by keeping the side exposed to the air (in the case of the red mold, where the vent openings are) warmer, so it will freeze AFTER the opposite side has frozen, pushing out as much of the assorted trapped gases, etc. as possible. I do this by placing a hot oven mitt on top of the mold.
And there ya go.
PS If you want to be really fanatical, Google "directional freezing cocktail ice." Have fun.