Our most popular and versatile Akoya pearl necklace is the Princess Length (18-Inch) 7.0-7.5mm necklace, which looks beautiful and age-appropriate for women from their mid-twenties up through adulthood.
Keep in mind that as women get older, their personalities and character are able to accommodate pearl sizes and jewelry styles that would look ridiculous on someone very young, so sizes 8.0-8.5mm through 9.0-9.5mm and higher are perfect for a mature woman. So really, it becomes a matter of budget and taste.
If your wife loves pearls and is familiar with them, then I'd highly recommend our Japanese 8.0-8.5mm Akoya pearl necklace which offers both elegance and prestige. If this is her first real pearl necklace, or she is very conservative in dress, then I'd recommend sticking with the 7.0-7.5mm or 7.5-8.0mm pearl necklace sizes.
These pictures below might be helpful in determining how the various sizes appear when worn.
Keep in mind, the model is a slim, tall female: I think about 110lbs, 5'8".
Akoya 6.0-6.5mm Pearl Necklace
Akoya 6.5-7.0mm Pearl Necklace
Akoya 7.0-7.5mm Pearl Necklace
Akoya 7.5-8.0mm Pearl Necklace
Akoya 8.0-8.5mm Pearl Necklace
Akoya 8.5-9.0mm Pearl Necklace
Akoya 9.0-9.5mm Pearl Necklace