The overall ratings of six Metals and Mining stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Mountain Province Diamonds’ (AMEX:MDM) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. Mountain Province Diamonds explores and develops diamond properties. In Portfolio Grader’s specific subcategories of Earnings Revisions and Equity, MDM also gets F’s. To get an in-depth look at MDM, get Portfolio Grader’s complete analysis of MDM stock.

Taseko Mines (AMEX:TGB) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Taseko Mines explores for and mines copper and molybdenum. The stock gets F’s in Earnings Growth, Earnings Revisions, and Cash Flow. Margin Growth and Sales Growth also get F’s. For more information, get Portfolio Grader’s complete analysis of TGB stock.

Western Copper and Gold (AMEX:WRN) earns a D this week, falling from last week’s grade of C. Western Copper and Gold is an exploration stage company, engages in the exploration and development of mineral properties in Canada. The stock gets F’s in Equity and Cash Flow. For a full analysis of WRN stock, visit Portfolio Grader.

This is a rough week for Pretium Resource (NYSE:PVG). The company’s rating falls to F from the previous week’s D. Pretium Resources acquires, explores and develops gold and precious metals resource properties. The stock also rates an F in Cash Flow. The stock price has fallen 10.2% over the past month, worse than the 3.7% increase the S&P 500 has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of PVG stock.

The rating of Gerdau (NYSE:GGB) declines this week from a D to an F. Gerdau S. A. is a Brazilian corporation that produces crude steel and related products. The stock also gets an F in Earnings Revisions. The stock price has fallen 8.4% over the past month. For a full analysis of GGB stock, visit Portfolio Grader.

United States Steel (NYSE:X) gets weaker ratings this week as last week’s D drops to an F. United States Steel is an integrated steel producer of flat-rolled and tubular products with production operations in North America and Europe. In Earnings Revisions, Equity, Cash Flow, and Sales Growth the stock gets F’s. Share prices fell 12.2% over the past month. As of Feb. 1, 2013, 22.6% of outstanding United States Steel shares were held short. To get an in-depth look at X, get Portfolio Grader’s complete analysis of X stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.