Dyed vs. Irradiated Pearls

I use a lot of freshwater pearls, and I have a question for the
experts. Is there a way to tell, other than if the dye is really
obvious, whether a non-natural colored pearl was colored using dye
or irradiation? (I hope I’m using the correct term here - the xray
method of coloring pearls is what I’m talking about - might be
called radiation.) Are certain colors more likely to be obtained
using one method rather than the other?

Also, if pearls are dyed badly, is there any way to save them? Could
I remove the dye, or lighten it somehow? I was thinking about
throwing some in my tumbler, but I’m afraid that in the case of
inexpensive pearls, it might remove too much of the nacre. I just
bought a large quantity of colored pearls, and some are lovely, but
others - well, the reason they were inexpensive is that the colors
don’t quite look right. If they can’t be saved, I guess I’ll string
some “little girls” bracelets and be happy that enough of the
strands are nice to be worth what I paid - I knew I’d be getting
some odd ones in this lot, I’d just rather not let them go to waste
if possible.

– Leah


Don’t throw them in the tumbles, even soaking them in water too long
can turn them into mush. If the pearl is one color over the whole
pearl it’s dyed. If it’s under 8mm and black, it’s dyed, you can
look at the drill hole with a loupe, there may be a dye line, or
look at the surface with a loupe, if the color is darker around a
blemish, they dye may have pooled there.

I recently saw some Tahitians that someone got a great deal on. You
could see a layer of lacquer in the blemish. The string being
colored is fairly obvious. Rub them with a chamois, look at them in
sunlight on a white background. Pearls with a nice nacre should be
luminous with just the buff of a chamois.

The fact that some of your pearls are off color should be a sign
that they aren’t dyed. Buff them with a chamois and bee’s wax, make
sure you get all of the bee’s wax off. Maybe a little TLC will help
with the color.

As for changing the color, I’ve heard of people using everything
from Color Magic, a glass paint, to finger nail polish and being
happy with the results.

Good luck.

Two~Twelve Tahitians
Wholesale/Retail Tahitian Black Pearls & Jewelry

Hi Leah

Over the last five years, increasing production of so-called
‘lasered pearl’ had appeared in the market. I understand it is still
kept secret but from what I gather, lasering pearl is a new dyeing
technique which took about half a year to one year to complete. To
detect this, you have to look for the dark peacock green or dark
purple patch just beneath the surface. Once you see it, you cannot

Irradiated pearl depending on the type of radiation applied. For
example, in the 1950s, (based on literature report) the Japanese were
irradiating pearl using Gamma ray i.e. from CO60. The irradiated
pearl that produced by this technique tend to be black or bluish-grey
with no residual activity. Then much later, in 1999, B-ray was used
to treat pearl turning it into black, silver, dark peacock green,
dark violetish red or bronze colour.

Here are some basic observation from my irradiated freshwater pearl
collection about 5 years, most of the core tend to be black, and
the nacre is greyish colour and slight peacock colour on the surface.
Spots of minute fractures (like percussion marks) could be found on
the surface of the nacreous layer and extenting into rainbow colour
just beneath the spot. More recently (2002), there is no ‘percussion
mark’ found but the peacock colour is very pronounce on the surface.
Under UVLW observation, irradiated freshwater pearl remain inert.


Very hot and humid Singapore

Thanks Tay and Misty for your responses!

I think that most of the pearls I have in this particular lot are
dyed, though the peacock ones might be irradiated. I’ll try buffing
the ones that aren’t as nice, and see if that improves them at all.

One more thing - pearls that have been irradiated will keep the
color permanently, right? I know that dyes can sometimes fade, but I
recall someone here mentioning that irradiated colors are permanent.
I believe the conversation was referring to but would I
be correct to assume that the same goes for pearls? Up to this
point, I’ve been using primarily natural colored pearls and bleached
white pearls, so I’m trying to be informed about my new stock so
that I can inform my customers about what they are getting.

Thanks everyone!

Hi Leah,

Regarding about the stability of the colour of irradiated pearl,
there is reference at the AGTA ‘The Gemstone Enhancement Manual’ that
the irradiated pearl is very stable. But I can’t remember reading
about researh or reference done on colour stability on irradiated
pearl. Can somebody enlighten me on that?

Gemstones on the other hand, as you probably would remember the
‘Anthrax spores’ case, where US post service sent all their parcels
to be irradiated. And a simple research was carried by GIA to find
out to consequence on the gemstone. Stones like Kunzite changes
colour from pink (before) to green (after) and sapphire light blue
(before) and yellowish orange (after), cultured pearl (saltwater and
freshwater) white (before) and grey (after). There are more example
to it in GIA past website.

Getting unbearably hot and humid Singapore

Is there a way to tell, other than if the dye is really obvious,
whether a non-natural colored pearl was colored using dye or

leah - when i started buying freshwater pearls by the kilo it seemed
wise to inquire as to how they were colored. the answer was simple &
sensible: clams & oysters are filter feeders: taking in water with
nutrients, straining the ‘food’ & exhausting the water - much like
some whales. the pearl ‘tank farmers’ started putting the various
dyes into the tanks with the bivalves (clams & oysters) to have the
color become as much a part of the nacre as possible. i was told
that this process replaced the old procedure of dying pearls after
harvesting because of the cleaning bills jewelers had to pay to
women when the dyes came off on clothing when the owners ‘glowed’ a
little too much on hot days [when married to rita hayworth, orson
wells declared that “she doesn’t perspire, she glows.”] however, if
you have doubts about certain colored pearls try this: fold & dampen
a paper towel & put in microwave oven. heat for 30 or so seconds.
remove & wrap pearls in hot towel. check for color transfer. good
luck -


who just returned from waaaay toooo many days in a 17’ canoe in the
gulf of mexico. camping on barrier islands. watching dolphin by day
& fireflies by night. eating what could be cooked on a 5 inch round
stove - dreaming of avocado salads & french silk pie. feeding the
ubiquitous ‘no-see-ems’ for which florida’s waterfront living is
notorious - known to drive sane victims over the edge in 45 seconds
flat. testing my envelope of personal restraint when passing over
very deep traffic lanes with the person who forgot the bug spray.