What is Pearl Luster?

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.

Pearls with a very high luster will generally show the following characteristics when viewed under a bare light with the naked eye.

Strong light reflections
Sharp light reflections
A good contrast between the bright and darker areas of the pearl

What Determines Luster?

A pearl's luster can be strong or weak. It depends on many different factors such as:


Cultivation techniques used
Cultivation place
Health of mother oyster
Length of time pearl is in oyster
Time of year when pearl is harvested
Pollution
Abnormally wide variations in temperature
Natural disasters such as earthquakes and typhoons
Type of oyster used

Judging Luster

Luster is a major factor in determining a pearl's value. The more lustrous a pearl is, the more high quality. it's perceived to be—and thus the more expensive it is. A truly lustrous pearl will have a jewel-like glow, with rainbow overtones. When a pearl appears too perfectly white or too dull and chalky, it is of low quality.

Here is some tips to identify pearls luster:


Look at the light reflections on the pearls. Usually, the less sharp and intense they are, the lower the luster. Sometimes, however, a lack of sharpness is due to surface blemishes, rather than the overall luster.


If possible, examine the pearls directly under a light instead of away from the light. This helps bring out their luster.


Look for the brightest and darkest areas of the pearls. Then compare the contrast between the two. 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 lusters 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. The luster not only varies from pearl to pearl. It varies on each pearl.


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 lusters. 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 will look better when viewed next to lower-luster strands than next to those of higher luster.