Vintage Yin and Yang mother of pearl pill box probably continental (silver?) 4 cm round 2 cm tall some age related wear we have a collection of pill boxes advertised separately see pictures Pill boxes have been used as jewelry boxes since ancient times, and are now sought-after collectibles. 
Yin and yang is a Chinese philosophical concept that describes two opposing but complementary forces that are always changing and in balance. The symbol for yin and yang is often depicted as a circle with one white and one black half. 
What does yin and yang represent? 
Yin
The female, cold, dark, passive power. Associated with the moon, water, darkness, intuition, softness, contraction, and yielding.
Yang
The masculine, light, and warm power. Associated with the sun, fire, light, activity, rational thought, hardness, expansion, and assertiveness.
How does yin and yang relate to health and wellness?
In traditional Chinese medicine, disease is diagnosed and treated based on the balance of yin and yang. 
The idea of yin and yang can help inform our approach to health and wellness. 
The balance of yin and yang is essential to harmony and health. 
How does yin and yang explain change? 
In Chinese thought, yin and yang explain what type of change something is undergoing. For example, yang represents expansion, growing, becoming more active, with more movement.
Other names for yin and yang
Yin and yang is also known as the Taijitu.
Mother of pearl, also known as nacre, is a lustrous, iridescent material that comes from the inner shells of certain mollusks. It's used in a variety of decorative and functional items, including jewelry, furniture, and musical instruments. 
How it's formed
Mother of pearl is made of calcium carbonate crystals, silk proteins, and other organic materials. 
It's layered like brickwork over the inner lining of the shell. 
The thickness of the platelets and the space between them give mother of pearl its iridescent quality. 
Uses 
Mother of pearl is used in jewelry, such as buttons and watch faces.
It's used in furniture, musical instruments, and decorative objects.
It's used in home decor, such as tiles on walls and floors.
It's used in handicrafts, such as tiny statues and keyrings.
Why it's used
Mother of pearl is durable and resistant to discoloration. 
It's a preferred choice for decorative and ornamental purposes. 
It reflects light in an interesting way. 
Some people choose instruments with parts made from mother of pearl because they think these sound better than other ones