@trongtoannguyen1 (23 August, 2015, 2:23 PM UTC):
It really depends what you're doing, what your goals are, and what circumstances you're in.

If you have the applicable 'major' discounts (I personally set a cutoff at 70%, but this is personal preference), and it's discounted towards something I want/need at the time (extra SDB, Strategic Units, etc.), then I usually go for that.

Short term players might find more use in getting Strategic units with their Diamonds, while long term players might find more use in getting more SDB (And you always have that option of buying Tactical Missiles for 24/7, multipurpose use).

If you are new to the game, do not spend your diamonds yet,

Wait till you learn more about spending them wisely.

I would recommend to save them and wait for a discount on engineers, you are going to need all 4 of them if you want to upgrade your base in this century.

Hello, Commander. I suggest you also to buy Improvised LZ. This building can increase your production of Fuel and Munitions up to 30%!

PAOKFANS said:

ΓΕΙΑ JOHN BLACK WHY LOST 650  DIAMONDS MY???

Hi, Commander.

Please, contact support on this issue. I'm sure, my assistants will give answers to all your questions.

If there are any mistakes, they will be corrected.

Use this link: http://bit.ly/Soldiers_Inc_Support

Hello commander black!! Im unable to find this improvised LZ & also the 'create alliance" tab in my alliance centre. 

I've logged in to create forums to help others BT found myself helpless in this basic query. Pls hop asap.

saranshjain74 said:

Hello commander black!! Im unable to find this improvised LZ & also the 'create alliance" tab in my alliance centre. 

Have you unlocked alliances as of yet, and are you joined to one?  Some of these buildings unlock after you've completed a certain level.. if this is a new base.

If memory serves me well, Alliances unlock after you place the Joint Operations Center.

Improvised LZ can either be found under the Resource tab in your construction menu, generally on the second page.

For those that do not buy diamonds, I'd suggest that you save them for things which give long term benefits, such as being able to build & upgrade 2 buildings at once.

Note: the 2nd and 3rd slot in the Medical Lab will be unlocked just by logging in, so best not to spend them on the medical lab slots.

(Having said that, I spend the diamonds to open the 2nd slot, and used the free one to open the 3rd.)

Generally speaking: reviving troops with diamonds is a waste of them, but might be worth while if you have the 75% discount active.

Anything you use them for that moves your game ahead is an OK use, but ideal is something that gives you disproportional advancement. This might mean buying something common / easy, such as 20 more S+D locations, because that happens to be the current active event. 

In other words: if you can use diamonds to win more diamonds: that is an exceedingly good use for them.

Likewise: buying the nuke because some guy just zeroed your base might give you lasting satisfaction, even if not highly effective.

This is first and foremost a game, so using them to have fun is never a bad idea.

Badlag247 said:

... long term benefits, such as being able to build & upgrade 2 buildings at once.

Or the even better long term benefits of investing them in your walls ;)

I spent over $400 dollars the past 2 days and still had 70K+ diamonds and left my computer for an hour or so and when I came back my diamonds were all gone except for 16K and no one else could have possibly has access to my pc...when I came back there were two tabs open in my browser to soldier inc. and I didn't even think that was possible because I tried it a long time ago to see if I could monitor badlands and drylands at the same time....I need my diamond re-imbursed because i have spent thousand on this game making Facebook rich and I will not ever play this again if I am not compensated....everytime I have a problem with a game issue support always give me some sad sack story and I always end up being the one that gets the shaft...I will start playing games on Steam and not have to spend this king of money.