Welcome to today's Petra Diamonds Q4 and Financial Year 2022 Trading Update conference call. My name is Jordan, and I'll be coordinating your call. If you'd like to register a question, you may do so by pressing Star followed by one on your telephone keypad. I'm now gonna hand over to Richard Duffy, CEO, to begin. Richard, please go ahead.
Thank you very much, and good afternoon, everybody. We are delighted that you're able to join us for Petra's fourth quarter and financial year-end of 30 June 2022 trading update call. I will begin by discussing our operating performance in the diamond market before handing over to Jacques, our CFO, who will cover the key financial points.
We will focus mainly on the full year numbers, commenting on quarter four itself where we think it is helpful. Both sets of Q4 and FY 2022 numbers are provided in the announcement. After taking you through this, we'll open up for Q&A. Please note that we have recorded our earlier call, which has been available on the website, if any of you want to access it later. Let's begin with safety, which is our number one priority.
We are very pleased with our much improved safety performance in financial year 2022. Our lost time injury frequency rate of 0.21 for the year improved by 52% from 0.44 last year. Lost time injuries fell by 44% to 14 for the year, and these were of low severity and mostly behavioral in nature. This improving trend supports the effectiveness of our remedial actions and behavior-based intervention programs.
We nevertheless continue to focus on providing a zero harm working environment, and we will continue to make every effort to reduce the risk of harm in the workplace. COVID-19 remains a risk to the health and safety of our employees, but one which we continue to manage with minimal disruption to our operations. Our focus continues to be on making vaccinations easily available and to encourage the uptake.
In Petra South Africa operations, 64% of the workforce have been vaccinated. It is worth putting this into context. Petra South Africa is well ahead of the South Africa double dose total of 39% of the population. We are encouraging take-up in Williamson in Tanzania, where 15% of our employees are vaccinated. Turning now to our revenue in the market.
We increased revenue from diamond sales by 44% for the year to $584.1 million. This was driven by a combination of higher diamond prices and the large number of exceptional stones. In total exceptional stones, being those that sell for $5 million or more, contributed $89.1 million to our revenue, up from $62 million in financial year 2021.
While our three and five year averages are $50.7 million and $39.2 million respectively. The increased frequency seen in the last number of years is attributed to the maturing nature of the C-Cut block cave, with mining activities across the full footprint of the Cullinan mine ore body.
Total revenue, which includes additional revenue from profit share agreements, amounted to $585.2 million compared to $456.9 million in FY 2021. During Q4, we realized a $1.1 million profit uplift from an 18.3-carat rough diamond that was sold into partnership in August 2021 for $3.5 million, with a 50% share of profits in the polished stones.
The final polished stones realized a net profit to the partnership of $2.13 million, contributing additional revenue of just under $1.1 million for our share. We have two additional partnership stones, being a 342.92-carat white, sold for $10 million in August 2021, and a 13.74-carat blue, sold for $5.7 million in May of this year.
These stones are still being processed, and we will provide an update once they've been sold. The 11% reduction in sales volumes compared to financial year 2021 is the result of the inventory built up in FY 2022 after the initial COVID-19 outbreak, which resulted in a higher than normal level of unsold diamonds going into financial year 2021. Tender volumes and resultant diamond inventories have now normalized.
As you will have seen from our own and other diamond producers' announcements, the diamond market has remained buoyant, reflecting the growing health of the diamond value chain since mid-2021, assisted by the release of pent-up demand following the pandemic, which is continuing to hold in the face of worsening global economic conditions.
As previously announced, tender six, which closed just before the year-end, achieved like-for-like price increases of seven points from the previous tender in May and 41.5% compared to last year. Demand in this last tender was robust across all sizes and qualities, with particular strength in the prices of white and colored gem quality stones, as well as an increase in demand for smaller diamonds.
To date, luxury goods appear to be relatively resilient in the context of the deteriorating macroeconomic backdrop, although we do expect some impact on demand, particularly in the U.S., which accounts for approximately 50% of the world's retail diamond sales. Despite these factors, which may create some volatility in the near to medium term, we expect the market to remain supportive given the prevailing structural supply deficit.
Our first tender in financial year 2023 is expected to close early in September. We will continue our flexible approach towards sales, and no decision has yet been made on whether we will maintain the same six tender approach we followed in financial year 2022 or revert to our more usual seven tenders for this year.
Production for the year was in line with guidance totaling 3.35 million carats, up 3% on the previous year. This largely reflects the resumption of mining at Williamson, which has now ramped up to full production. While quarter four production was in line with quarter three production, there are a couple of factors explaining the reduction of 6% versus Q4 in financial year 2021.
Firstly, financial year 2021 included mining from the higher grade CC1 East area at the Cullinan mine. During financial year 2022, production was sourced exclusively from the C-Cut area. Mining from the CC1 East area will once again resume on completion of the CC1 East Sub-level Cave project, which we announced in February of this year, which is due to start contributing run-of-mine tons going into financial year 2025.
Secondly, we experienced a reduction in the grade recovered at Cullinan mine, resulting from the change in the makeup and maturity of the ore within the C-Cut block cave footprint as production progresses from the southwest to the northeast. This has introduced a higher proportion of ore known as coherent or pyribol kimberlite from the central and northeastern portions of the C-Cut that is both lower grade and higher in density.
As a mitigant to prevent overloading in the plant recovery stream, we deliberately reduced the volume of tailings treated, which is typically also higher density material. We are carrying out studies to better understand these changes in ore makeup together with mitigation measures. Production guidance for the financial years 2023 to 2025 remain unchanged.
It is also worth mentioning that as previously announced, the convergence of tunnel forty-one at Cullinan mine has been remediated, and we continue to monitor the area to determine when we will be able to re-access the tunnel. The closure of tunnel forty-one has been factored into our guidance of 1.6-1.8 million carats at the Cullinan mine for financial year 2023.
At Finsch, as previously reported, we have largely mitigated the waste ingress and the implementation of enhanced drill, blast, and draw controls has led to steady production between quarter three and quarter four, albeit with some reduction in run-of-mine grade. Overall carat production increased 3% year-over-year, totaling 1.275 million carats. As previously announced, we are continuing to implement the business reengineering project to enhance margins at Finsch.
We are now also implementing the business reengineering project recommendations at Koffiefontein, with the aim of providing sustainable operations until the mine's closure. This has unfortunately necessitated some job losses to align the operation with a reduced tonnage profile. That process was concluded at the end of June, and the mine has started on a new shift configuration with this reduced labor structure. In parallel, and as previously announced, we are exploring a responsible exit from Koffiefontein through a sales process that commenced in quarter four.
As part of this process, we have received non-binding expressions of interest, which we are in the process of evaluating. We expect to conclude the sales process before the end of this calendar year. Should a successful sales transaction not be forthcoming, we remain committed to running the mine to closure.
Let me briefly touch on Project 2022, which has now formally and successfully been concluded. As you know, we launched the project in July 2019 to run for three years to deliver a target of between $100 to $150 million in net free cash flow. I'm very pleased to confirm that we will have exceeded that target, and generated net free cash flow in excess of $200 million.
The final number will be confirmed in our preliminary results announcement in September. While this is a significant milestone for us, the key takeaway from Project 2022 going forward is that we have now fully embedded the culture and improvement initiatives and processes in our operating model.
This will ensure that we have continuous improvement at the heart of this operating model, and as a key component of our cultural DNA to deliver ongoing benefits for the group. Turning now to Tanzania and a brief update on the independent grievance mechanism, or IGM, and framework agreement at Williamson. We have implemented remedial initiatives and are putting in place the IGM and restorative justice project in the community.
We expect to complete our engagements with the government of Tanzania and local stakeholders on the IGM in coming weeks, and we'll then appoint the various individuals and organizations that will make up the IGM with the aim of making it operational towards the end of this calendar year. Further details on this are provided on our website.
The framework agreement entered into towards the end of calendar year 2021 is still subject to certain Government of Tanzania approvals. Similarly, the MoU entered into with our local partner, Caspian, is also subject to certain conditions before becoming effective. This has taken longer than expected, but we are working together to complete the outstanding matters.
I will now hand over to Jacques, who will run through the numbers as well as touch on cost inflation, currency, and load shedding. Jacques.
Thank you, Richard, and good afternoon, everyone. I will touch briefly on the balance sheet, which has strengthened further and in particular, highlight our consolidated net debt, which has further reduced to $40.6 million, down from $107 million at the end of March and $228 million at the same time last year.
Gross cash balances ended the year on $288 million and unrestricted cash was $271.9 million at the end of June. The ZAR 1 billion RCF or revolving credit facility with Absa Bank has been finalized and is now fully effective. It remains undrawn with an available balance equivalent to some $61.5 million at the end of June 2022. Net debt is stated after diamond debtors, which ended
At a balance of $37.4 million compared to $38 million at the end of FY 2021, driven by the timing of our Tender six, which occurred at the end of our reporting period. Diamond inventory on hand was valued at $53.5 million, down compared to March 2022, which again reflects the timing of our Tender six. Cost inflation is affecting the mining industry globally and not just our operations in South Africa and Tanzania.
We are monitoring cost increases very closely, and I'm glad to say that the impact is somewhat limited given we have a three year labor agreement which extends until June 2024. We have, through Project 2022, put in place a rigorous and disciplined cost management.
We are also benefiting from the exposure to a weak rand with some 80%-90% of our OpEx and 90%-95% of our CapEx denominated in rand. On the guidance front, we are able to reaffirm our operating and cost guidance to 2025 as set out on a year-by-year basis at the Investor Day in February.
However, the numbers are stated in real FY 2022 terms, so do not include inflation, but do assume a US dollar rand exchange rate of 15 rand, which is, of course, quite a bit stronger than the current rate of closer to 17 rand to the dollar. We also highlighted today that around $12 million of spending for capital items planned for FY 2022 will now be spent in our fiscal year 2023 due to longer lead times than expected for certain capital equipment.
Overall project timeframes as well as capital spend will not be affected. The news of load shedding in South Africa suggests things are worse than they in fact are for major industrial consumers such as mines. We are not subject to load shedding, but are rather required to curtail our power consumption.
At the current levels of load shedding, our excess processing capacity at both Cullinan Mine and Finsch allows us to reduce our processing during periods of load curtailment, which, apologies, while maintaining mining at full production. We then subsequently catch up on processing when the curtailment ends. With that, let me hand back to Richard to wrap up with our outlook.
Thank you, Jacques. In conclusion, I would just like to reiterate our very strong year with 44% revenue growth and excellent cash generation, resulting in our consolidated net debt reducing by 82% to $40.6 million compared to the end of FY 2021. We look forward to providing you with details of our financial performance at our preliminary results announcement in September.
We take comfort from the fundamental strength of the market, which we expect to remain supportive, although there may be some volatility in demand in the short to medium term. We reiterate our guidance and look forward to this next phase of value-led growth as we build on our strengthened and stable operational platform with a considerably healthier balance sheet that together are expected to provide further cash generation to fund our CapEx programs and provide for further deleveraging. That concludes the overview, and I would now hand you back to the host for our Q&A session. Thank you.
As a reminder, if you'd like to register a question, please press star followed by one on your telephone keypad. If you change your mind, please press star followed by two. Please ensure you're unmuted when speaking. Again, for any questions, that's star followed by one on your telephone keypad. We have no questions registered via the phone lines.
Well, thank you very much. If there are no questions, I would just like to thank everybody for dialing in. If there are any questions that you subsequently have, please feel free to reach out to our investor relations team and we'll follow up with you on the back of that. Thank you very much for your participation and we'll talk again in September.
This concludes today's call. Thank you for joining. You may now disconnect your lines.