If you were holding portfolio investments in silver in the first few weeks of May, it didn't feel like a silver lining. The white metal plunged in price nearly 30 percent in just two weeks of trading - after a spectacular run-up earlier this year.

So, could silver be set for a rebound?

First of all, why should there be excitement over silver, the cheaper cousin to gold? Michael Purves, chief market strategist and head of derivatives research at BGC Financial, explains that silver's price correlates closely with gold, although not with base metals or other commodities.

While gold is a key holding for many hedge funds and other professional investors, such as billionaire George Soros, silver rarely is a holding at all, Purves said.

Why is this?

Silver is generally not held by central banks, while gold is. Silver also has a higher proportion of industrial and nonmoney uses than gold does. The metal has been considerably more volatile than gold. Finally, the silver supply-and-demand dynamics are not well-understood.

"We will not be surprised to see many funds and governments diversify their gold holdings into silver in 2011," Purves said, "as gold finds new highs and is more than 45 times more expensive than silver."

Some Wall Street types are predicting that silver will reemerge as "hard money," like gold. Investors across the spectrum recognize that gold prices continue to climb, and will increasingly turn to silver as a valid source of currency that can't be devalued by central banks printing paper money.

However, commodities such as silver and gold are incredibly volatile investments. After running up 27 percent just in April, silver retreated 30 percent in the first two weeks of May - in hugely active trading.

CME Group, which oversees silver trading at its Nymex exchange, citing a bubble in the making, restricted the silver margin (investing with lent money) requirements four times in the span of several weeks, as speculators flocked to the metals markets.

As of Monday, silver closed at $35.10 a troy ounce, up .56 percent.

There are a few ways to invest in silver, but some of these vehicles have incredibly onerous tax consequences. So beware. Because precious metals are considered collectibles by the IRS, once you sell some of these funds, you'll be taxed as much as 28 percent upon the sale.

Some silver funds are closed-end funds, which can trade at a premium or discount to their net-asset value, meaning you might be paying slightly more or less than the value of what's actually in the fund, depending on how much demand is out there in the marketplace. Don't be surprised if the closed-end fund is not trading at the price you expect.

Among the exchange-traded funds out there are the widely held iShares Silver Trust, the Sprott Physical Silver Trust, ETFS Physical Silver Shares, and PowerShares DB Silver Fund. The ZKB Silver ETF and the Claymore Silver Bullion Trust are others. Or investors can investigate buying silver metal-mining stocks or commodities-trading companies, such as the Glencore International Plc, which had its initial public offering just last week.

One can invest in a commodity index, such as the S&P GSCI or the Dow Jones Commodity Index. An index tracks the performance of a basket of commodities. The value of these indexes depends on the commodities that constitute the index, and this value can be traded on an exchange in a similar fashion to stock index futures.

"An advantage of trading a commodity index is that, unlike trading the commodities directly, it is a very liquid investment. It is also accessible to many investors by virtue of being traded on an exchange," said Rumi Masih, global head of the Strategic Investment Advisory Group of JPMorgan Asset Management.

There are three main commodity indexes: the Goldman Sachs Commodity Index (S&P GSCI), which is more than 70 percent energy; the Dow Jones-UBS Commodity Index (DJ/UBSCI), which is 33 percent energy and more than 30 percent industrial and precious metals, and the Thomson Reuters/Jeffries CRB Index (TR/J CRB), which is 40 percent energy, 20 percent metals, and 40 percent agriculture commodities such as corn, cotton, cattle, and soybeans.

If you think silver has more room to grow, then there are investment options for you.