EVEN though the prices of apartments and offices have rocketed over the past couple of years, the mammoth revaluation of Sino Land's non-China real-estate portfolio is being seen by some sceptical fund managers as a little ''ritzy''. Following a revaluation prepared by property consultancy Chesterton Petty, Sino Land has announced a 109.4 per cent rise in the group's net tangible asset value to $32.03 billion, compared with a book value of $15.29 billion in its June 30, 1993, balancesheet. The increase in net asset value was based on a $6.53 billion increase in the value of Sino Land's investment property, a $6.02 billion increase in the value of its real estate still under development, a $3.55 billion rise in the value of unsold apartments, and a $529.6 million increase in its listed equity investments based on market prices on December 20. Sino Land has been regularly revaluing its investment property assets at current market prices, as is normal practice, but has been keeping the rest of its portfolio at book value. Nobody is questioning the professional integrity of Chesterton Petty; rather, how much credence should be given by investors to revaluations themselves. The Sino Land portfolio may well have been a true reflection of property prices on December 20, but would the group raise that much if it decided to sell its portfolio tomorrow? Probably not. The market would be flooded. The company's net tangible assets per share rose to $16.32 as a result of the revaluation, against its $12.90 closing price on Monday, when it was announced. A C.Y. Leung & Co revaluation of Henderson Land's assets announced in October saw the valuation of its property portfolio jump to $42.69 a share, shattering market estimates of about $22. Its share price has since jumped more than 140 per cent, helping it record the largest percentage rise among Hang Seng Index constituent stocks last year. It will be interesting to see whether Sino Land's share price now follows a similar path, or whether other property developers will jump on the bandwagon. Investors greeted the revaluation by sending Sino Land's share price up $1 or 7.7 per cent yesterday to close at $13.90.