Opals meaning vary with the varying of their colours. This is also the case for all crystals that come in many variations of colour.
Unfortunately I am unable to find detailed usage for this particular stone. Generally these darker forms of crystal are used for a sense of grounding more stabalising energy field.
This bracelet is 17cm
Grey Opal stretch bracelet
For all my jewellery I would advise that in order for your item to keep its shine and brilliance that all jewellery be kept away from chemicals, chlorine, salt water and perfumes. Even too much sun exposure for the natural crystals can cause the beads to loose their colour.
For elasticated bracelets it is advised that bracelets be rolled on and off the wrist instead of stretched, as over time stretching the elastic can cause the bracelet to loose its shape.
Most metals can oxidise and discolour so its best to keep them in an air tight bag