I love the effects of gun blue on copper! I use Perma Blue, found in the US where ever gun supplies are sold, so check all the sports stores. The chemical name - Selenium Dioxide.
I dump it in a jar, use it as is, put the lid on and keep it in the cupboard until next use, alongside my jar of lemon juice/salt for cleaning copper. Not too strong a smell, no need for ventilation or gloves, poison if you drink it but otherwise safe for normal grown-ups. Read the label and don't be stupid. yada blah blah disclaimer *grin*
Step by step -
**First drop the jewelry into lemon juice, with a dash of salt, to clean off skin oils etc. About a minute, keep watch, I never time anything. No specific amount of salt, maybe 1/2 tsp to one plastic lemon (found in the produce area next to real lemons, easy to use, not costly, use any real lemon juice you prefer). Salt is not mandatory, but it seems to work faster. The cleaning step can also be done with ketchup, vinegar, salsa anything acidic.
I like the smell of lemons.
**Rinse Well, and pat dry so you don't dilute the gun blue.
**Drop the piece in the gun blue and keep watch. In 1 to 5 minutes the piece will be black. You can pull it out at any point in between for less darkening. You can re-dip if it's not dark enough. You can paint it on spots if you feel you can't dunk it or want spots, but painting works Very Slow, with repeated paintings. Be patient and persistent.
The warmer the metal/liquid, the faster it works. In the cold winter, I first immerse the metal in hot water, pat dry quickly and then the gun blue.
**Rinse Well !!! and rub with a soft cloth, an old t-shirt is perfect. Very Messy if you darken all the way to black, beware for nice clothes.
Rub until all the mess is gone and you get the highlights you want.
Rubber gloves help control the messy hands.
The process of wiping is usually enough to get the highlights showing. The rest I let happen naturally. The dark in the crevices lasts forever.
I tried tumbling a big batch one time, first with dry rice, thinking I'd get some friction, then with stainless shot and Dawn, neither was particularly successful, the rice really not at all. But the soft cloth made pretty quick work of it after all.
**Finish up with a Sunshine Cloth for beautiful shine. Not required, but oh so pretty!
Forever after, the jewelry just needs a quick rub with a soft cloth to be ready to wear.
Never Ever Never walk away from either jar in progress. If the phone rings, pull the jewelry out and drop them in the water until you can come back and finish. I left one piece 4 or 5 minutes and it got Very powdery black and took much longer to clean. Very Messy! I haven't experimented with longer, but it would be messy at least, don't know if the metal would be damaged.
If you use containers with lids for your Perma Blue and lemon juice, you can just put the lids on and store in the cabinet. No need to refrigerate the lemon. Both last for years, even if they look disgusting, (the plastic lemon type will last years, it has preservatives, don't know about fresh lemon juice).
I found the middle size canning jar (wide mouth, pint size?) at Walmart in the kitchen section, not grocery section, works really well, deep enough to cover a bracelet, wide mouth for inserting pieces. The jars hold two bottles of Perma Blue or two plastic lemons very nicely, so the liquid is deep enough to cover the project while it sits.
To date, I've done all kinds of quartz family stones, turquoise, fresh water pearls, malachite chips and glass.
The malachite chips got a little powdery looking and a bit dark, but they were small chips so it was hard to tell. A toothbrush and sunshine cloth restored most of their shine, so use discretion.
One cab I would have sworn was white quartz lost all shine and absorbed a whole lot of the blue color. Totally trashed. I have no clue what the rock really is.
Dyed red coral came out kind of dull and a little darker.
I tried a couple of small fresh water pearls, and they came out fine.
When in doubt, try a sample bead before dunking the whole project.
You can also paint the Perma Blue in certain areas to spare the delicate rock, but it's a PITB and Very Slow to turn dark.
Fresh water pearls and a shell moon
Princess Leia Goes To The Beach
Turquoise, raw rubie and quartz
Turquoise, raw rubie and quartz
This is the raw copper version
This is The Princess after Perma Blue