Palladium

It's Latin name is Palladium. In the Periodic Table it is abbreviated to Pd. It was discovered in 1803 by William Hyde Wollaston of England.
It was named after the asteroid 'Pallas' which was discovered at about the same time and from the Greek name 'Pallas', goddess of wisdom.
Palladium is mainly used in the Zebra range of jewellery. They use an alloy of 50% Palladium, 40% Sterling and 10% Copper.
There is no British assay hallmark for Palladium.
It has similar properties to Platinum - it is equal in its endurance to corrosion and also in its brilliant colour.
It does not tarnish in air, and is the least dense and lowest melting of the platinum group metals. When annealed it is soft and ductile. Cold working increases its strength and hardness. It is used in some watch springs.
An allergic reaction to Palladium is next to impossible. " It's value is equivalent to 14ct gold.
Other uses for palladium are; catalyst for hydrogenation and dehydrogenation reactions, dentistry (crowns), used in fine instruments such as watches and surgical instruments, electrical contacts.

Nickel

As a result of various problems associated with nickel sensitisation in clothes and jewellery, the European Community (EC) Nickel Directive (76/769/EEC) was enacted on 20th July, and became law in the EU on the 20th January 2000, starting with body jewellery.

The directive was devised due to fears about allergic reactions and sensitisation to nickel, and has been designed to reduce any problems caused by this metal. The directive simply put is as follows:

Items intended to come into contact with broken skin (i.e. piercings) are restricted to a mass of 0.05% nickel. Items intended to come into close and prolonged contact with skin are restricted to a release rate of 0.5ug/cm2/week of nickel.

With body jewellery this directive is in force. Our body jewellery suppliers have certificates from the Assay Offices showing that their products comply with the directives. They also have documentation showing that they are running schemes to constantly check their products. It is recommended that titanium is used in fresh piercings and steel to be used once the skin has healed.

Note that a nickel reaction will show up as red broken skin or a rash and it can be sore and itchy. A green/black band e.g. when wearing a ring, on the skin is not a nickel reaction. It is the sweat in the skin and the atmosphere reacting with silver and is not harmful.