18k (75%) gold is the purest form of gold used for jewelry (pure 100% gold is 24 karats by definition). 18k means that 18 out of the 24 parts that make up the gold are pure gold. The most common hallmark stamps for 18 karat gold are 18K or 750 that indicate 75% gold purity. 18k yellow gold is an alloy made up of 75% pure gold and 25% alloy (12.5% copper, 12.5% silver).
Mediterranean Red Coral
Red coral, or precious coral, is a type of coral species mainly found in the Mediterranean Sea. It is typically the only kind of coral used in high jewelry.
Coral is a type of marine invertebrate that lives in compact colonies of countless identical single polyps (reefs). Red coral grows in rocky sea-bottoms that have minimal sedimentation. The environments are dark, such as the depth of the sea or a cavern or crevice. They can be found 10 meters to 300 meters below sea level. What’s very interesting is just how old red coral is. Sizable reefs of red coral take over 100,000 years to form. As for which seas, the Mediterranean Sea is the most famous source of red coral. However, red coral also grows in the Pacific Ocean (i.e. Japan and China).