Many of you, just as I was, find metal descriptions gibberish so let me take a shot at explaining to you about metals.
1. Iron: Iron, pins, rings, some bead caps, cord ends, and such are often made with Iron. Because this is the cheapest one in the market, it makes it fantastic to learn on.
Con: Rust, sticks to magnet, and seems to be only second to the weakest (aluminum) metal - only as to jewelry making. In the description for metal components, information about the metal finish is listed. If you have nickel allergy, please look for Nickel Free. Must have information about the metal alloy and metal plating.
2. Brass: pins, rings, chain, and many other findings. In comparison to Iron, brass is stronger, meaning 20 Gauge Iron strength will be different than 20 Gauge Brass. The price for the brass findings at wholesale is about double the price of Iron. Budget Beads do not charge double for brass, but a small difference in price.
Pro: Availability. Affordability, no rust, sticks less to magnet.
Con: The information about the lead cadmium and nickel information is mostly unavailable.
3. Stainless Steel (201, 304 and 316/316L)
The numbers listed in the stainless steel refers to the grade of the steel.
201 is mostly made for sink, refrigerator panel and such.
304 is the most common Hypo Allergenic Stainless Steel
This is what is refer to as "food grade." Used to make utensils and such.
316/316L this is surgical steel, also Hypo-Allergenic Stainless Steel.
Again, when compared, the strength of 18 gauge copper, iron, brass, and stainless steel are much different.
Pro: Hypo-Allergenic, no tarnishing, strong-I compared 20 gauge (.8mm) to about 14 Gauge copper wire.
Con: Expensive, especially plated stainless, e.g. silver, rose gold, gold.
Stainless Steel in Steel color is about double the price as the brass items. When the stainless steel findings are plated, it will double or triple the price of the stainless steel color.
Keep in mind, that ALL, I mean, ALL Stainless Steel including Hypo-Allergenic stainless steel contain nickel (Appx 10%) and cadmium. The cadmium is in ALL stainless steel. This heavy mineral keeps the stainless steel from corrosion. The human body is very acidic so extra cadmium is in the surgical steels.
Just recently, I have noticed that some stainless steel is marked as "lead cadmium and nickel free. I do not think the metal itself has changed, but they are plated with real silver, gold and rose gold, titanium, rhodium, etc.
4. Sterling silver (925)
I am sure everyone knows this. Sterling silver is 92.5% silver, and 7.5% is mixed copper, nickel, and such. The tarnishing on metal including sterling silver is due to the copper content.
We mainly see copper wires used in wrapping, but true copper findings are hard to find. They are available if you look.
Most copper wires have plating which may contain lead, cadmium and/or nickel free so again, if you are concerned, please look for items free of the harmful elements.
Tin alloy, pewter alloy, zinc alloy. The "alloy" refers to mixed metal so most of times, full contents are not disclosed, but sometimes they are marked lead, cadmium and nickel free so you must look for at the minimum nickel free because many people have nickel allergy. Most Tibetan Style alloys belong in this category. We do our best to carry lead, cadmium and nickel free metals, but they are more expensive, can't find them in all colors. These recent days, nickel free silver plated items have gone up. They explained that the silver color metals without nickel, at least for chains, must be "plated" 7 times.
Lastly, when buying pins and rings, I suggest the diameter of wire is minimum 0.7mm to prevent out of line rings, and pins too weak to stay on the piece.
I hope this explained a little about the metals, the cost, and availability.