Colorado's Amendment 64 will be part of the state constitution in a matter of days with Washington state also making their new law official as well. With medical marijuana legal in 18 states plus Washington D.C. and now recreational use by adults legal in two state many wonder if there is an investment opportunity in the marijuana industry.

In interest of full disclosure this is not intended as investment advice and is not meant to encourage you to purchase or endorse any of the stocks below. As with all investments stocks come with risks, consult your broker.

Some like the CEO of GrowOp Technology, Derek Peterson says, "Call it the ‘green rush'.The industry is expanding, and there are all kinds of investment opportunities.”Although some have recently become too excited about making money off marijuana stocks with one recent example being Medbox (MDBX), a patented marijuana dispensing machine, skyrocketing then falling. The stock went from a pre-election day price of under $4 all the way up to over $200 and then was down again by 90%.

If you're serious about investing in this small but growing industry there are many companies to chose from including pharmaceutical companies, growing supply companies as well as regulation.

Colorado Springs based Cannabis Science (CBIS) is developing marijuana based medicines for HIV/AIDS and cancer patients. While GW Pharmaceuticals (GWPRF) currently makes available their marijuana based oral spray, Sativex.

Some companies like Medical Marijuana (MJNA) offer ways for patents to get their medication without the effects of smoking offering infused sodas, ice creams and other treats.

Other companies are also benefiting from the potential of legal marijuana, such as the company first mentioned, GrowOp Technology. They aren't a standalone niche stock like some, but is the subsidiary of indoor agricultural company Terra Tech (TRTC). The company Medical Marijuana (MJNA) not only includes patented products with cannabinoids, but also the testing, labeling, tracking and production.

High Times recently noted the companies Converted Organics Inc. (COIN) and GreenGro Technologies, Inc. (GRNH) for their involvement in industrial hemp. There are also large tobacco companies like Altira (MO) long rumored to have plans to enter the marijuana market. As well as companies like Smokefree Innotech (SFIO) already in the smoke-less and vaporization market.

Will any of these stocks make you rich overnight, or even in your lifetime? Probably not, although there are sure to be some winners and some that see gains. Some may experience market turmoils like Medbox, while others see real long-term gains. Others, like Altria Group, might make a good investment for some even without any public plans of cannabis products.