Recently started a new playthrough using All The Mods 6 modpack and got annoyed by the fact that many mods I like to use are not supported beyond MC v1.12.2. So I dropped back to punt and started a new 1.12 instance in MultiMC with the FTB Ultimate Reloaded pack. Got my fav mods loaded and started a new world. All was going well until I started mining and discovered that most upper tier ores like redstone and gold were all requiring a diamond pickaxe rather than iron. Methinks that don't bode well and sure enough, when I found my first diamond it now needed a diamond pick. So how in hell-o am I supposed to get a diamond pick if I can't get diamonds without one? Same thing turned out to be the case for obsidian, it now needing an obsidian pick. Catch-22?
I tried to plow through what I thought would be likely mod configs that might make such a change but came up empty. So I switched to a different modpack not of any FTB variety - specifically a Technic pack "The 1.12.2 Pack" - which, gotta say, the inclusion of ambient sounds here is freakin' sweet - and BAM!, ran into the same issue. Is this a MC specific change now and would such a change apply retroactively? I can't imagine such, unless I'm completely missing some new mechanic of the game, and believe it's got to be a mod tweaking something(s) (like how GregTech can make some recipes infuriatingly difficult. And no, I don't use GregTech) but I'm at a loss. I searched the MC forums for "diamond pick" and found a thread from someone wanting to know how to make ore mineable with only a diamond pick and there it mentioned tweaking "yourBlock.java". What/where this is is kinda outside my comfort zone but willing to learn. This certainly wasn't happening the last time I played. Mind you I'm doing survival mode at normal setting here so nothing exotic in that respect. Anybody else seeing this?
I downloaded the FTB Ultimate Reloaded modpack with no major changes (aside from video settings) and don't seem to be having any of those issues.
The tooltips overlay does say you need a diamond pickaxe for diamond ore, for whatever reason. But mining it with a regular iron pickaxe works fine. Same with redstone ore. And obsidian seems to be mined fine with a diamond pickaxe.
So the tooltips overlay may be broken / misleading.
This is definitely not a vanilla mechanic, which makes no sense whatsoever (as you said, how you you even obtain ores in the first place if you can't even mine them. Sure, you could trade or find items in chests but that defeats the entire purpose of mining and make progression way too hard for most players), and Mojang never backports features to old versions, and even if they did they would release a new patch (one special case is 1.6.4, which backported a fix for structures not being saved when world generation changes, which had originally been made for 1.7, so people could update to 1.7 without breaking witch huts, eyes of ender, etc. No actual features were backported though, nor were any older versions fixed, including 1.6.1 and 1.6.2).
Otherwise, I could find very little information on this issue but it sounds like you are supposed to use modded tools to mine diamond; for example, this thread says you need "steel" (for a different modpack), or you need to "research" or "level up" in order to reach the required "mining level", which seems to be a common thing in modpacks (I've never played any so I have no idea how they alter game mechanics, and there is very little documentation provided on their download pages, just some very general descriptions).
Recently started a new playthrough using All The Mods 6 modpack and got annoyed by the fact that many mods I like to use are not supported beyond MC v1.12.2. So I dropped back to punt and started a new 1.12 instance in MultiMC with the FTB Ultimate Reloaded pack. Got my fav mods loaded and started a new world. All was going well until I started mining and discovered that most upper tier ores like redstone and gold were all requiring a diamond pickaxe rather than iron. Methinks that don't bode well and sure enough, when I found my first diamond it now needed a diamond pick. So how in hell-o am I supposed to get a diamond pick if I can't get diamonds without one? Same thing turned out to be the case for obsidian, it now needing an obsidian pick. Catch-22?
I tried to plow through what I thought would be likely mod configs that might make such a change but came up empty. So I switched to a different modpack not of any FTB variety - specifically a Technic pack "The 1.12.2 Pack" - which, gotta say, the inclusion of ambient sounds here is freakin' sweet - and BAM!, ran into the same issue. Is this a MC specific change now and would such a change apply retroactively? I can't imagine such, unless I'm completely missing some new mechanic of the game, and believe it's got to be a mod tweaking something(s) (like how GregTech can make some recipes infuriatingly difficult. And no, I don't use GregTech) but I'm at a loss. I searched the MC forums for "diamond pick" and found a thread from someone wanting to know how to make ore mineable with only a diamond pick and there it mentioned tweaking "yourBlock.java". What/where this is is kinda outside my comfort zone but willing to learn. This certainly wasn't happening the last time I played. Mind you I'm doing survival mode at normal setting here so nothing exotic in that respect. Anybody else seeing this?
I downloaded the FTB Ultimate Reloaded modpack with no major changes (aside from video settings) and don't seem to be having any of those issues.
The tooltips overlay does say you need a diamond pickaxe for diamond ore, for whatever reason. But mining it with a regular iron pickaxe works fine. Same with redstone ore. And obsidian seems to be mined fine with a diamond pickaxe.
So the tooltips overlay may be broken / misleading.
This is definitely not a vanilla mechanic, which makes no sense whatsoever (as you said, how you you even obtain ores in the first place if you can't even mine them. Sure, you could trade or find items in chests but that defeats the entire purpose of mining and make progression way too hard for most players), and Mojang never backports features to old versions, and even if they did they would release a new patch (one special case is 1.6.4, which backported a fix for structures not being saved when world generation changes, which had originally been made for 1.7, so people could update to 1.7 without breaking witch huts, eyes of ender, etc. No actual features were backported though, nor were any older versions fixed, including 1.6.1 and 1.6.2).
Otherwise, I could find very little information on this issue but it sounds like you are supposed to use modded tools to mine diamond; for example, this thread says you need "steel" (for a different modpack), or you need to "research" or "level up" in order to reach the required "mining level", which seems to be a common thing in modpacks (I've never played any so I have no idea how they alter game mechanics, and there is very little documentation provided on their download pages, just some very general descriptions).
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?