I'm a scuba instructor so for giggles I did the maths!

Based on these densities:

    Gold Density: 19.32 g/cm3
    Lead Density: 11.34 g/cm3

We now need to understand how much water is displaced by a kg.

    Gold volume: (1,000 / 19.32) ≈ 51.75 cm3
    Lead volume: (1,000 / 11.34) ≈ 88.18 cm3

1kg of gold displaces 51.75 cm3 of water. 1kg of lead displaces 88.18 cm3 of water.

    Fresh water: 1000 g/litre
    Salt water:  1025 g/litre

In fresh water:

    1kg gold = (1000g negative buoyancy - 52g water displacement) = 9948g negative buoyancy
    1kg lead = (1000g negative buoyancy - 88g water displacement) = 9912g negative buoyancy

In salt water:

    1kg gold = (1000g negative buoyancy - 53g water displacement) = 9947g negative buoyancy
    1kg lead = (1000g negative buoyancy - 90g water displacement) = 9910g negative buoyancy

As a scuba-diving weight, gold is less than 1% more efficient (by weight) than lead.

It's counter-intuitive: gold is nearly twice as dense as lead, but the importance in scuba diving is the weight of the, er, "weight", vs the weight of the water it displaces (Archimedes principle).

Gold weights per kilo are a tiny amount more efficient than lead per kilo, but much smaller and much sparklier. Anyone who wants to donate me a gold weight-belt, please be assured I would display it to its full magnificance. Around 8kg would be fine :-)