hi sexbomb,
some good rules to run by when it comes to buying opiates, heroin comes in all kinds of colours and powdered forms so looking at it does not help much at all. I would suggest buying a maquis reagent tester. available at all good stores near you.
that way you can screen out many different types of substances, such as amphetamine etc.
The tester does not indicate what strength the substance is though, if injecting or otherwise i would go by what someone once said regaring opiates : "you can always do more later, if you have not done enough... If you done too much, you wont be doing much later (OD)"
always start off small, each person has a different biopsycho makeup. what is enough for you may be more than enough for someone else or not enough for some one developing a tolerance. 0.1 gram or 0.05 of a gram may be enough to get you going depending on the purity and strength of the substace and how you decide to administer it to yourself.
guessing from the needle pic you put in the opening post, i would start very slow. Sometimes people will sell diverted opiates such as that from prescriptions or even worse diverted from opiate treatment clinics (diverted from mouth and reformed, bacteria and all being injected straight into the body)
good rules for opiate users is:
*Never use alone
* always use new injecting equiptment from a needle and syringe program, never share spoons either as you never know if someone else is reusing a dirty needle
* pill filters are a great way to reduce the chalk and bacteria while injecting,
*you cant tell the dose by looking at a substances colour, reports by another user are said from the context of their experience
* use much less than you think, you can always re dose later and learn from that experience to judge what may be a right starting point for you next time should the gear be the same
*should someone drop call an ambulance straight away,
* know first Aid if posible, have a contingency plan with the other person you are using with " if i drop (OD) call the ambulance"