There is a lot of choice out there in pendants and earrings, because it it a commonly offered gift. Sadly, much of what is produced and sold in retail stores lacks true quality, being mass produced using low grade materials. Such pieces are not made to be worn over a lifetime.
Custom making a truly unique piece of jewellery is of course completely different. It is more suited to the person who wants better quality and wishes to have an item that will last.
Some diamond content is always good in this area, but can be accompanied with coloured gemstones, such as sapphires. Setting a budget level can help to determine what is possible, but you must remember to also keep a little in reserve to provide ( in the case of a pendant ) for a reasonable chain to hang the pendant from.
There is not really a particular cost level that would be typically spent in this area so really setting a budget and talking about the best use of the funds could be a helpful start.
Simple pendants and earrings could start from around $2,000, but of course for a really large or intricate item with a lot of diamond content, that cost can rise rapidly. With a pendant or earrings in precious metals and diamonds, a budget in the $3-5 k area is not unreasonable and will buy you a pretty piece of jewellery.