It depends, and there are several factors that should go into making your decision. A description of the properties of each metal will help you decide which is better for you.
Platinum is what is regarded as a “dead” metal, meaning, when you move it, bend it, or mechanically manipulate it, it stays where you put it for the life of the object. This property of platinum is mandated by US law, which dictates that jewelry made of platinum must be at least 90% pure. Most platinum used in jewelry in the US is 95% pure. Platinum is also very dense, which is both a blessing and a curse. Being dense makes it very resistant to wear. Under normal conditions, a platinum prong holding a diamond, or any other stone, may very well last for generations, never needing to be re-tipped or replaced. The downside of platinum is considered by most to be its high price. Depending on the type of gold used, platinum is around three times more expensive. However, the low maintenance required of platinum jewelry ends up evening the price of the two metals over time.
Gold, unlike platinum, is much more an alloy. Twenty-four karat gold is pure, but far too soft for use in jewelry. It is more the consistency of aluminum foil. So, for practical purposes, gold used in jewelry is alloyed with other metals to make it more durable. Fourteen karat gold is 14 parts gold, 10 parts alloy. Ten karat gold is 10 parts gold and 14 parts alloy, and so on. The alloys that are added to gold to strengthen them, also impart some undesirable properties, the most important being metal memory. Metal memory means that a metal will always try to return to its original shape. This is especially problematic with settings made of white gold, that use prongs to hold the stones. The prongs will try to slowly straighten themselves out over time. This means that the stones will eventually become loose. This is not as much of a problem with other types of stone settings, like channel, pave, and flush. We would recommend having any piece of jewelry, with stones set in white or yellow gold, to to have the stones checked for tightness periodically, by a competent jeweler with extensive jewelry repair knowledge.
The basic properties discussed in this post should help guide you to a decision on which precious metal is best for your piece of jewelry. For more thorough explanations of each metal’s properties, please see our continued posts of this subject.