Think of the many colours of the sea, changing with the sun rising to sunset.
Aquamarine, and Apatite are similar to what I described above.  Colours will change under both natural and indoors lights. Their shades are calming and could easily compliment any of your attire  
 
This item is designed with 7 rows of mixed aquamarine and apatite, sprinkled with 32 - 2 mm, 18-carat gold beads.
Closed with a 14-carat yellow gold clasp.
Necklace length: 45 cm