If you have to fuss around before the effect, the spectator thinks you are doing something fishy and
it lessens the impact. It turns the effect into a puzzle, which is ok if that's what you want. If
you could somehow hide the get ready, it would be very magical.
In magic there are a few things that are important. Three of which are; practice, practice and practice. Additionally, there is a little something called misdirection or "direction". Direct their attention slightly away as you're getting ready. Simply ask something like "Is this 18 or 24 karat gold?" (As you look them in the eyes.)