Smoky quartz is an excellent crystal. It's main uses are for grounding, helping to protect one's energetic field, and for clearing energy. It is an essential crystal for anyone who is working with crystals and/or complementary medicine of any description.
Whilst it's primary purposes are about energy management, smoky is also a wonderful stone for grounding high-voltage spiritual vibes onto Earth. Smoky is essentially clear quartz that has been naturally irradiated. Be mindful to avoid buying the smoky that has been artificially irradiated.
This particular piece weighs about 395g, and measures 9.5cm highest x 8.5cm widest, and is 4.5 cm deepest, and has quite a few rainbows in it.