What is solid gold?
24K is the only true solid gold option. Gold is a very soft metal so it's popular to blend gold with other alloys such as silver, copper, nickel, and zinc to make it stronger and more durable for jewelry. The most popular gold used in jewelry is 22K, 18K, 14K and 10K. The higher the number the more gold content but you also sacrifice durability. All gold Fire + Mineral jewelry is made from 100% recycled 14K.
What is gold-filled?
Gold-filled is a layer of gold pressure-bonded to a base metal usually brass or silver. Since it has 100% more gold than plated it doesn't flake or tarnish and lasts a really long time. It's almost indistinguishable to the eye from solid 14K and since 14K is the only metal that touches the skin those that can wear gold should be fine with gold-fill. It's a great economical alternative.
What is gold-plated?
Gold-plated is a very thin layer of gold put over a base metal. It's an economical alternative to the above options but the quality of the jewelry and the reaction you may encounter vary. Gold-plated is a standard in costume jewelry and not the best for everyday wear as the gold layer will wear off and turn over time.
What is gold-vermile?
The difference between gold-plated and gold-vermile is that vermile is a thin layer of gold over sterling silver. The color may still change with regular wear but the sterling layer is better for those sensitive to base metals and gold-plated jewelry.
I personally choose to only use 14K gold or 14K gold-filled in all of my designs as the quality of both will last my customers for years to come and reduces the chance of reactions on the skin. Hopefully, this helps shed a little light on a tricky subject! If you're interested in learning more about silver I have a post on that here.