Each weekday, TheStreet.com Ratings updates its ratings on the stocks it covers. The proprietary ratings model projects a stock's total return potential over a 12-month period, including price appreciation and dividends. Buy, hold or sell ratings designate how the Ratings group expects these stocks to perform against a general benchmark of the equities market and interest rates. While the ratings model is quantitative, it uses both subjective and objective elements. For instance, subjective elements include expected equities market returns, future interest rates, implied industry outlook and company earnings forecasts. Objective elements include volatility of past operating revenue, financial strength and company cash flows. Crystallex International ( KRY) engages in the exploration, development, mining, production and processing of gold, primarily in Venezuela. It has been upgraded to a hold from a sell. Despite an increase in cash flow of 1.65% in the first quarter of 2007 compared with the same period a year ago, the company is growing at a slower rate than the industry average of 261.8%. Net income decreased 17.6% in the same quarter compared with the same period in 2006, dropping to $6.7 million from $8.2 million. Although the company's stock price has increased 42.3%, TheStreet.com Ratings team does not recommend additional investment at this time. Crystallex had been rated a sell since June 2005. Taser International ( TASR), which develops and manufactures the eponymous electronic control devices used in law enforcement, corrections facilities, private security and personal defense, has been upgraded to a hold from a sell. The company's revenue rose by 10.1% in the first quarter of 2007 compared with the year-earlier period. However, this growth does not appear to have trickled down to the company's bottom line, as evidenced by its stagnant EPS. Taser's debt-to-equity ratio is 0.00, implying successful management of debt levels. Its return on equity of negative 4.4% in the first quarter of 2007 is lower compared with the same period last year, a sign of weakness within the company. This return on equity also significantly trails that of both the industry average and the S&P 500. Taser had been rated a sell since April 2007.