Apparently, when the Monterey Bay National Marine Sanctuary was created, jade collecting became illegal. After locals and rock lovers complained a compromise was effected in 1998 that lets you take what you can carry, so long as it's from below the high tide mark and so long as you haven't used more than a hand tool (no jackhammers!) to remove it.
Your vision of a cove might echo ours prior to our trip, which is something like a quiet, protected inlet with a small beach. Jade Cove could better be described as 'a tiny, wave-beaten area at the bottom of a treacherous path -- that last part of which has mostly given way -- covered in huge, slippery boulders that have tumbled recently from the unstable cliffs looming above it."
Yes, that's the entire cove in the picture below.
Our prospecting was impacted not just by the tiny space available to us between the cliffs and the sea. We faced the added hazard of the onset of the three-day Valentine's weekend storm that brought five inches of rain to Big Sur.
We grabbed a few greenish pebbles and we're waiting to find a knowledgeable geologist to tell us what we've found. Some might be jade, but most are likely to be serpentine, which has the virtue of being the California State Rock, but the vice of usually being deposited with asbestos running through it. We did see some lovely native plants, though. Including a lot of wonderful dudleyas like this one.