Pearl Luster is the factor that provides the pearl with its true beauty - it's that mysterious inner glow that seems to emanate from the center of a genuinely high-quality pearl.
Usually, a pearl's luster is a combination of surface reflection and a glow that really does come from within - from the many layers of nacre built up over time inside an oyster.
When viewed under a bare light with the naked eye, pearls with a high luster will generally show the following characteristics.
-Strong light reflections
-Sharp light reflections
-A good contrast between the bright and darker areas of the pearl
What Determines the Luster of Pearls?
The luster of pearls depends on many different factors such as:
-Cultivation techniques used
-Health of mother oyster
-Length of time pearl is in oyster
-Time of year when pearl is harvested
-Abnormally wide variations in temperature
-Natural disasters such as earthquakes and typhoons
-Type of oyster used
Judging Pearls Luster
Luster is the main factor in determining the value of a pearl. The sheen and quality of pearls are directly proportional to the price. Truly shiny pearls will have a jewel-like luster, with the implication of the rainbow. Pearls are not of high quality when they are too perfectly white or too dark and chalky.
Here are some tips to identify pearls luster:
Observe the reflection of a pearl. Usually, the clarity of a pearl is in proportion to its luster. It should be noted that lack of clarity is sometimes due to surface imperfections rather than poor luster.
Check pearls directly under light. The light helps to reveal the brilliance of the pearl.
Contrast the brightest and darkest areas of the pearl. The lower the contrast and the milkier the pearl, the lower the luster. This is one of the quickest and easiest ways to spot low and very low luster. Milky-looking pearls are sometimes sold in "high quality" stores. Be aware that their luster is low.
Compare the luster of the individual pearls on the strand. They will almost always vary somewhat in luster. The luster quality of a strand is determined by its overall appearance, not just by one pearl. High-luster strands, however, should not have low- and very-low-luster pearls. If you find a strand you like that happens to have a pearl or two with an obviously lower luster than the rest of the strand, ask the salesperson to have them changed when they are strung with a clasp.
Roll the pearls slightly so you can see their entire surface. Every pearl has a different luster.
Try the pearls on and check if you can see the highlighted spots on them from a distance (say 10 feet/3 meters). You'll be able to if the pearls are of good quality.
If possible, lay the pearls alongside other strands and compare the luster. This is most effective when you already know the relative quality of the comparison strands. Keep in mind that your impression of a strand will be affected by the pearls it is compared to. A strand look better when viewed next to lower-luster strands than next to those of higher luster.