The global prices for a variety metals, such as copper, nickel, and titanium, have soared in the past few years, as the enormous growth in demand from China, combined with somewhat constrained supply sources, meant gold rush times for metal producers. But there are signs that the long price run may be nearing an end, and perhaps reverse itself dramatically.

That change has already occurred in the market for nickel, which after a huge run up in price since 2003 has seen the global market price drop by about 50% in just the past three months. Demand from China and other areas of the globe slowed, in part due to changes in the production of stainless steel that meant less nickel was used in each ton produced. In a pricing market largely driven by the futures exchanges, speculators quickly bailed, resulting in a stunning price reversal.

In the past few years, many purchasing managers felt that the notoriously cyclical commodities markets had ceased to operate as they had for most of history, given the unprecedented price gains and price changes moving in only one direction – up.

Always cited as the key factor in this scenario was the enormous and seemingly unquenchable demand for metals by China. The country has been in the midst of a sustained boom in both manufacturing and physical infrastructure development that required metals in enormous quantities. But it turns out that the laws of supply and demand haven’t quite been repealed, as the surging prices caused buyers worldwide, including the Chinese themselves, to look for alternative materials or production strategies.

For this reason, some now believe copper prices are also due for a fall. With copper prices rising some 400% since 2003, users are finding alternatives. An increasing number of plumbing and building firms, for example, are moving to plastic or PVC piping. Other industrial users are replacing copper with aluminum, removing copper demand that may never return. The Wall Street Journal reports that a Chinese firm has found a way to use a copper-aluminum alloy in air conditioning equipment, rather than straight copper, which if widely adopted could reduce the use of copper in that industry significantly.

Though opinions vary, experts seem to believe that this “diversion” from copper could soon cut the global demand somewhere between 5 and 10 percent. This would have a huge downward pricing effect on copper prices, as copper producers simultaneously try to expand output in the face of the current sky high pricing environment.

Though commodity experts at places like Goldman Sachs expect the price of copper to remain above $6000 per metric ton over the next few years, buyers would be smart to heed the lessons of the recent meltdown in nickel prices. Many companies had stockpiled nickel itself or finished products such as stainless steel, thinking it was a smart investment in the face of ever rising prices. Now, with the rapid and steep decline in nickel prices, these firms are sitting on raw materials that could be bought for half of what they paid, or stainless steel inventories that are now worth a lot less than what is on the books, as stainless market prices have dropped as a result of lower nickel costs.