The valuation basis depends upon the client's circumstances and requirements:
an insurance valuation represents the replacement value of articles,
a willing-buyer/willing seller valuation is the basis adopted where the parties (usually private) express a willingness to effect a sale without the article being exposed to the open market, eg when an article is being sold/transfered with a property as part of a 'going concern',
a current market valuation is based on the figure that an article is likely to achieve when offered for sale at auction or to a trade buyer,
an inheritance tax valuation is the basis adopted when articles are subject to inheritance tax,
a valuation for rental purposes is adopted when articles form part of a rental agreement.